The Pono Player and Promises Fulfilled Page 2

Pono_Player_Photo_TyllBlindTesting

What is Pono?
Neil Young defines the word "Pono" for us on this page:

Pono means righteous. It is a Hawaiian word, the one, the pureness.

If there's a standard by which the Pono player should be judged, it's whether or not it righteously serves that sacred thing we call music. That's a lofty goal. I think I'll start with my most recent Pono music experience.

There's a bar here in Bozeman called Colonel Black's Lounge that features a full-size jazz band on Sunday Nights. The room in which they play is about 40' x 40'. The band takes up about half the room, and there's room for about 40 people in the other half with seating at a few tables but mostly standing. I like to arrive early and get a seat at one of the tables where I'm virtually knee-to-knee with the lead sax player. The band is made up of about a 50/50 split of music majors at Montana State and older players some of which are professors at MSU and others are just local pro and amateur musicians. I'd rate the band as "pretty damned good." I really enjoy the music.

But I also really enjoy the experience professionally. I evaluate music reproduction gear every day, but, when you live in Montana far from major cities it's very special to have the opportunity to hear a 17 piece jazz band ripping it up from five feet away. I didn't bring my level meter, but it must be breaking 100dBspl regularly. 100dBspl is loud and if I listened to headphones or speaker that loud it would likely be a painful experience. It's an amazing thing to hear music that loud with absolutely no distortion. The natural sound of human lips at the end of buttoned brass tubes is gorgeous, I drink in the acoustic intensity with ecstatic relish.

The jazz band at Colonel Black's Lounge on Sunday night is Pono!

And all audio reproduced electro-mechanically pales in comparison. If there's a huge gap in audio performance anywhere, it's between live acoustic (unamplified) sound and sound that's electro-mechanically reproduced. It doesn't even compare. And that's an important point: reproduced audio can't, and probably shouldn't, be compared to live acoustic sound. There is an art to recording and reproducing audio, at every stage it has to be understood that the live event (if there even is one) cannot be accurately reproduced but must be re-interpreted to exist in this alternate medium that allows us access to music without having the musicians present.

This art starts in the recording studio but extends out to the people designing the reproduction gear that we use to experience the art of music. At every point along the way very subtle choices are made. The recording engineer might gently slide the fader up a minuscule amount on the bass player; and Charlie Hansen (the Pono Player's designer) might move a decoupling capacitor just slightly closer to the collector of a transistor. These people will tell you these subtle changes are important to the perception of wholeness and beauty in the art of music. Being Pono in the world of audio reproduction, in my view, is knowing how to make a wide variety of subtle adjustments that, when combined, allow us to suspend our knowledge that the artificial reproduction is inferior to the real sound, and allows us to fully engage in the intensely human experience of enjoying the music.

A subtle thing is objectively small, but can have potent subjective effects.

And the converse is also true. Let's say you go for a hike in the beautiful back-country and a small piece of grass gets caught in your sock. It just barely touches your ankle, but you can feel it poking you. You look for it, but it's so small you can't see it and you can't get rid of it. If you're not very good with your sense of non-attachement, this tiny blade of grass might make you nuts by the end of the day and significantly degrade your hiking experience.

My point here is that two things are at play: the objective mechanism, and the subjective experience. They are not tightly coupled like gears in an engine; they are related and dependent only insofar as you will or allow them to be. This is an important concept and I've written about it more fully here.

Blind testing back and forth between gear may give me the opportunity to hear the differences between products, but it's difficult because most gear is only subtly different. But when it comes to long-term listening, those subtle differences can mean the large difference between an irritated or ecstatic experience.

The articles that have been published by others criticizing Pono for lauding the virtues of the small differences between file resolution or between a Pono Player and an iPod are ignoring the importance of subtlety in an art form. The jackbooted ignorance yet again tries to crush the rose of beauty. For shame.

So here's the deal: in my view, to be Pono with regards to music reproduction, you have to know how to execute subtle things that makes the music more accessible to your root human being. At some point, depending in part on how much your willing and able to enter the experience, the sum of those subtle things will allow you enter a mode of sensation in which you deeply engage and experience the art. To mash up my words with some of Neil Young's words: It's the difference between recognizing the music, and resonating with it. A Pono piece of gear just makes it easier to enter the meditation on the music. The improvements over other gear may be subtle, but they're important because they help you make the big jump into a deep engagement with your music. But that big jump happens in your head and heart, it's not in the player.

Is the Pono Player Pono?
In a word, and from my viewpoint, yes. The Pono Player is a wonderfully musical file player when used with appropriately matching headphones. In terms of its sound, I would say that for me it's without equal in the realm of hand held portable players in terms of pleasurable listening. In my judgement the Pono Player has absolutely fulfilled the Pono brand promise of being a righteous vessel for deep, and dare I say soul satisfying, experience with your music.

Is the Pono Player Perfect
In a word, no. While the use interface is functionally a bit above average (many players in this price range have horrible user interfaces), it's also small and easy to fat-finger your way into flustrating errors; it auto-rotates too easily; it's shape is not pocket friendly; the Pono software is little buggy; blah, blah, blah. Apart from the sound, the Pono player is just reasonably adequate.

I do want to mention that I personally like the triangular shape of the Pono Player. Yes, it's not easily pocketable in your jeans, but it works fine in a coat pocket. The big advantage for me is the ability to easily see the display and operate the player on a desk surface without having to pick it up.

The more I experience the Pono Player, the more it reminds me of a pair of Sennheiser HD 600s and the Bottlehead Crack. There are all sorts of ways in which both of these products fall short of a reference quality reproduction, but this pairing is almost universally praised by headphone enthusiasts as an inordinately musical combination. The Pono Player is like that to me: It's simple and relatively inexpensive, it's not a hot rod or race car delivering ultimate performance, but it delivers an exquisite sports car bimble through the English country-side listening experience way beyond what the price tag might have you believe.

Are the Astell & Kern Players Pono?
I'm going to say, yes. They may not be quite as musical as the Pono for me, but others might quite like the slightly superior bass punch, for example. Remember the differences are subtle and personal taste does come into play; I'm not sure one can speak authoritatively on something so subjective. And frustration with the Pono user interface, or the fact that it's uncomfortable in your pocket might be just annoying enough that the super sweet user interface, unbelievable feature set, and more convenient shape of the AK players end up delivering an overall more satisfying experience with your music. It depends on each individual's value system. This is not a black and white issue.

Recommended Headphones for the Pono Player
Having made a issue of selecting headphones carefully earlier in this article, I thought a short list of headphones I would recommend might be in order:

  • Philips Fidelio X2 ($299) - Around ear, open acoustic. This is a great headphone for home use (will not isolate you from outside noise) with a well balanced sound signature that will easily be driven by the Pono Player. Review here.
  • Shure SRH1540 ($499) - Around ear, sealed acoustic. An extraordinarily comfortable headphone to wear, the Shure SRH1540 has a "U" shaped response with a judiciously emphasized bass and treble. The tuning may become too emphatic at high listening levels, but makes for a terrific experience for those wise enough to know that loud listening may lead to hearing damage and listen at lower levels. Review here.
  • NAD VISO HP50 ($299) - Around ear, sealed acoustic. The NAD VISO HP50 is one of my favorite headphones. It's slightly warm response mimics the way good speakers sound in a well acoustically treated room. Good bass punch and a relaxed enveloping sound. Review here.
  • Audio Technica ATH-MSR7 ($249) - Around ear, sealed acoustic. The ATH-MSR7 delivers extraordinary transient response and detail. Leaning a bit to the cold side, bass lovers will not like these cans, but lovers of acoustic jazz, chamber music, and choral work will revel in their layered detail and imaging. Review here.
  • Audio Technica ATH-M50x ($179) - Around ear, sealed acoustic. For the cost conscious the ATH-M50x is a godsend. These cans throw a strike right down the middle and keep your wallet intact. Only a very modest lack of refinement and liquid coherence separate it from the excellent cans above. Review here.
  • Sennheiser Urbanite ($199), Beats Solo 2 ($199) - On ear, sealed. Great for use on the move, the Sennheiser Urbanite and Beats Solo 2 are both terrific headphone with tasteful bass emphasis. Those looking for a solid thump when out and about will likely enjoy either. Choose based on the small differences brought out in the full review of the Urbanite and Solo 2.
  • Aurisonic Rockets ($249) - In-ear, dynamic driver. With a very clean and articulate but overall neutral sound, the Aurisonic Rockets will let the beauties of the Pono Player shine through. Titanium build and Aramid fiber cable give the Rockets a bullet proof build. Not yet reviewed.
  • Philips Fidelio S1 ($99) - In-ear, dynamic driver. A great choice for the budget conscious, the Fidelio S1 is slightly warm in-ear monitor that will always be gentle on the ears. Review here.

For Balanced Operation
These headphones will need a special cable for balanced operation, but will require no modifications otherwise.

  • Sennheiser HD 600 ($349) - Around ear, open acoustic. A long time favorite of headphone enthusiasts the world over, the HD 600 may lack the bass extension and treble resolution of some headphones, but a glorious overall balance and ease make them a terrific partner for the similarly musical Pono Player. Review here.
  • Audeze LCD-X ($1699) - The most efficient of Audeze's high-end planar magnetic headphones, the LCD-X is capable of achieving solid listening levels with the Pono Player in unbalanced mode. But add a balanced cable and you'll be rewarded with music that's tighter, more composed, and blacker between the notes. Review here.

For further recommendations see InnerFidelity's "Wall of Fame".

Balanced cables and cabling advice can be had from Cardas, Moon Audio, and WyWires. Because the Pono Player is so new to market, you may have to call these companies to get current information on compatible cabling configurations available.

Summary
The Pono Player was a sublimely musical surprise. While the letter of Neil Young's words were, in my view, a significant over-promising of the Pono Player's performance—I don't think anything could have objectively lived up to his "on a mission to save music" zeal—I do think the Pono Player delivers superbly on the spirit of his intent. This player delivers the sonic goods way beyond it's price, and to my ears is the most satisfying handheld digital file player I've yet heard.

When I compare it side-by-side in blind tests with other players I find its smooth yet resolving treble to be its stand-out characteristic. I will also say that the sonic differences I heard between players was objectively quite subtle—all the players I used sounded quite good. But in long term listening I found the subtle beauties of the Pono Player to elicit a significantly superior emotional connection to the music for me. This may very well be personal, but having heard products before that are widely held by enthusiasts as musical, I've got to think the Pono Player will fall into that category.

On the down side, while the user interface is better than average capable in its functions (so many digital audio players have horrid user interfaces), I find its small size a somewhat frustrating affair for my fat fingers. The triangular shape is not ergonomic in a jeans pocket, but I found it fine in a jacket, and the ability to use it on a desk is superior to having to pick up a flat device to read or manipulate the screen.

Yessiree-Bob, the Pono Player gets a hearty recommendation from me. John Grandberg was in the midst of doing a large survey review of digital audio players as I started this Pono review. I had him send me back some of the players for comparisons here. I hope to return them to him shortly with permission to include the Pono. My hope is that we can come to a meeting of the minds and produce a "Wall of Fame" page for portable players. In my mind, the Pono will make the WoF, but I have to confer with John before that accolade can be conferred. Until then I'll just leave you with the knowledge that I love the sound of the Pono Player. If you want a simple but excellent sounding portable player that won't break the bank the Pono Player is an outstanding choice.

Editors Note: Time constraints are such that I have published this article without comments from the manufacturer, which I think is important in this case. Please come back and revisit this review in a week or so as there will be some additional comments from the manufacturer by then.

COMPANY INFO
Pono
1501 Mariposa Street, Suite 312
San Francisco, CA 94107
(800) 611-0580
ARTICLE CONTENTS

COMMENTS
Jazz Casual's picture

Really. This is an audio review well worth reading imo.

Tyll Hertsens's picture
What is it that seemed worthy to you?
Dreyka's picture

This truly is an exceptional review and I cannot thank you enough for spending what must have been a huge amount of time on this. I wish all DAC/Amp reviews were like this and it would really give validity to the high end market if more people would take the same approach as you. A balance of blind ABX testing with subjective opinions is the way forward for reviews and I wish more professional reviewers would take the time to do it.

Jazz Casual's picture

That's not to suggest that your other reviews aren't because they are, but I found this one especially so.

Tyll Hertsens's picture
I'll take that to heart.
Tyll Hertsens's picture
Having thought about this for a day now, I think one of the important differences about this review is there's a frigging huge story attached to it. I'm going to very positively review the new Noontec headphone next week....but geez, Neil Young isn't behind the thing.

This is basically an amazing story to see unfold.

IRL's picture

So what about hi-rez files. Does gentler filter help at all? ofc a $400 player got to sound good even with 320k mp3 but people are bashing it mainly because they are trying to make 16/44.1 seems worthless and getting people to buy hi-rez files from their store, not the player itself. so is there an audible difference with hi-rez files using pono?

Tyll Hertsens's picture
Unfortunately all my test tracks that I've regularly used for 20 years are 16/44.1, so I did al the blind listening tests between gear at 16/44.1. I'll have to edit the article to add that soon, sorry. I did listen to a number of hi-res tracks in casual listening and heard the type of things I always do---smoother, more organic, more pleasing/less annoying than 16/44.1, but by objectively subtle amounts.

I'm going to have to work on solidifying some high-res test tracks. The trouble is it's very difficult to get tracks of the same music at legitimately differing bit rates that are known to come from exactly the same source master. But I will...well, I already am working on it. Just not quite completely equipped yet.

Also, the gist of your question is about the nature of hi-res files, not the Pono Player per se. I will, however, make comments on that some time in the future. I don't think I'm done with Pono yet.

bernardperu's picture

How about converting hi rez to cd-quality? Or just converting 24/96 to 24/48 or 16/48?

That way you make sure you have the same master.

veggieboy2001's picture

Commendable (IMHO) that you would ignore all the hype (both positive & negative) and take the time to actually LISTEN...and to go to such extensive lengths to make it a blind test. This seem to be truly a "synergy" player, where all the parts make up the whole, so I wonder how it would be effected using other amps...would it kill the musicality?
As always, a great review...thanks.

Three Toes of Fury's picture

Howdy Tyll...first up: outstanding review! Thank you for taking the time to outline your test rig..always cool to better understand test methods.

Question: do you have thoughts on Pono vs Fiio? The test rig photo shows the X5 but i didnt see it listed in the summary section. Fiio is a pretty interesting contender to me for this market. Their upcoming update to the X3 is getting solid reviews on headphone sites. Wondered if Pono Pono'd it or not?

Have a blast at Camjam! Cant wait to hear/see reports from it!!!

Peace .n. Living in Stereo

3ToF

potterpastor's picture

Would the Sennheiser Momentum 2.0 be a good match for the Pono, or is HP50 still better?

Tyll Hertsens's picture
I've got the Momentum 2 Wireless---which I like quite a bit as a BT headset---but haven't heard the wired only version yet, so I can't answer the question.
ednaz's picture

Reading about your testing process made me start to feel sorry for you. It sounds like a process that would squeeze the joy out of listening to music, something you clearly love to do. That said, glad you are willing and able to take it on, and I hope you've got some kind of "purge" process for you to get out of forehead on the table eyes scrunched closed mode and back to "ahhhh, lovely music" mode. Better you than me.

Really good analysis of the Pono, and as a former big band touring musician, the big band analogy connected for me. I like my music to sound like I'm IN the band or orchestra (sitting behind the violas...) I like speakers that sound that way (dipole or open baffle), ditto headphones. As my headphone and player collection has grown, I'm starting to experience what you described about player/headphone pairing issues. My first customs were Westone ES-5, and I love them with iPods, and with a couple old Sansa and Microsoft players, also with my computer. When I got a Fiio X5, they suddenly seemed a little more harsh and sharp edged. I got a set of ACS triple-drivers for travel, and they pair beautifully with the Fiio, but with iPods they don't sound as good to me as the Westones. But very good with my computer and new iPhone. Humph. Complexity is not what I was hoping for.

Will be very interested in the impressions from the multiple player and headphone testing that's in progress. Would be interested in seeing Pono or Astell&Kern and other players compared to the other option for road warriors like me, which is a nice portable USB DAC and laptop.

tony's picture

Everything sounds superb playing "A" music, even the 900mhz. Sennheiser RS120s ( I own two pair ).

However the vast range of music out there is probably B and C class music. ( I'm using Bob Katz's rating system of A,B,C quality )

If I, or probably everyone else, could see all music being A Class I could then see a clear path to owning a Stax 009/Blue Hawaii system.

I scour the World hunting down A Class recorded music, I probably have one or two dozen CDs arriving per week, maybe 10% are in the A range, another 10% to 15% are B range.

Pono is suggesting ALL music could be Class A which seems nonsense to me. Bob Katz is also shining some light on music quality for you and all of us ( thank you Bob ) .

I just counted up my A Class collection, I own 1,320 A Class pieces of recorded music! , that's more than I've ever owned in my lifetime!!! I won't quit building this library, more arrive every week but that group represents only about 15% of my entire collection. phew, that's a LOT!, no way could a vinyl person have this large a collection, nooooooo way!! Tod the Vinyl Junkie has 12,000 Vinyls, he'd need to add another wall of storage system to expand, I just need a few more TBs.

The "Promise of Pono" mandates/requires every piece of music to have been created by people like Bob Katz and we already know that ain't the case.

Maybe if N.Young was on the Board of Apple with full control of iTunes and also on the Board of Sony with full control of all their library and on the Board of all the other outfits like RCA, DG, etc., maybe then he could make a Promise like he's making.

Great music sounds great on everything, even the iPhone6+. I'm sure that great music will sound good on the Pono player, I don't need a review to inform us of that. I need the reviewers to tell us if the promise of all music being available as "A" Class Recordings is now realized.

Is that Promise realized? Don't answer, let Bob Katz answer that.

Thank you for trying.

Tony in Michigan

Charles Hansen's picture

Hi Tony,

I totally understand your point and would urge you to listen to a (well burned-in) PonoPlayer. One of the main goals of Ayre has always been to let the equipment get out of the way of the music.

Over the decades we've gotten better and better at that. We've reached a point where I feel that one can play any recording and truly engage emotionally with the music and artist, regardless of the quality of the recording.

It's not that the music sounds "good" through some euphonic filtering, it's more a case of just noticing that the recording is not that great and then enjoying the music anyway. My theory is that most high-feedback designs are actually perturbed in some way by poor recordings and add additional artifacts that detract from the listening experience.

I've found that with the PonoPlayer that regardless of the recording quality, one will end up as Tyll found himself in the opening of his review -- unable to type as the music was too compelling to push it to the background.

Naturally I've a dog in the fight here, so please don't take my word for it. Go and listen for yourself and decide.

But it sure makes shopping for music a lot easier when the recording quality is not so important! I will admit that the ultimate experience is a superb recording of an incredible piece of music performed with complete commitment by the artist. So great recording, engineering, and mastering is still an important pursuit. Yet the ability to engage with less-than-stellar recordings gives one a huge freedom. YMMV.

Cheers,
Charles Hansen
Ayre

Tyll Hertsens's picture
Good to see you here, mate. Thanks for your comment!
Charles Hansen's picture

You seem to have a well-behaved group here, which is a welcome change from many forums. I'm not sure how long I'll be able to contribute as I've a lot on my plate. But it's always fun to meet new people.

Cheers,
Charlie Hansen

tony's picture

Thank you for writing back,

I just had a look at your company and your product line ( thru a Google search ), this may be the first time I've had any encounter with Ayre, you look like a high quality/first rate operation.

I think I can believe your little player sounds good. I suspect you lads only make superb, probably superb is who you are.

If you lads discovered a way to make all that B & C music more listenible I'm definitely interested, I suspect that everyone that manufactures little players is also keen to have a close look at your workings. I'm saying "IF", i.e. if someone ( I know ) calls me up to say your little player is knocking their socks off and I "gotta" hear this thing! Contrasting that with the consistent linage of Audiophile Discoveries the Press have been presenting since the days of 4 Channel ( 1975ish ).

The Pono product packaging isn't consistent with the "performance" promise or the Ayre product line ( in general ) but is consistent with a low price. I saw the slide top wooden box and thought of a $10 Microscope. Hm, well ok, Koetsu packaging is crap too, no big deal. I've sold scads of Koetsu, nobody ever complained about their crappy little wooden boxes, including me.

I suspect that amplification today is quite good, we may be assigning +/- values to shadings of "A" level electronics performances, the transducers ( loudspeakers ) seem far more capable than those of a few decades past. I might ask if anyone still manufactures low quality Audio stuff, they won't last long ( I'm thinking ) .

Well, OK, I promise, I'll have a good listen to one of your players, a well burned in player and I will have a look at one of your converters ( DAC ) when I get the chance ( I live in no-man's land, fly-over country ).

If you can make Art Tatum recordings listenable I'll be a convert.

Thank you again for writing,

Yours,

Tony in Michigan

BarbecueGamer's picture

Very well written! An absolute fantastic review! The amount of work that went into this is stunning. Great work Tyll.

Say, have you seen Linus's from LinusTechTips review of the Pono? I highly recommend it, I think you'd get a kick out of it. Here's the link- https://www.youtube.com/watch?v=6VQUFCCcQ4A

Tyll Hertsens's picture
Saw it shortly after it posted and thought it was pretty entertaining. Unfortunately, I didn't get the sense that I understood the real value of the product.
Chrisg2229's picture

Wow, Linus is annoying; his voice really grates on my nerves.

I couldn't listen for more than a minute or so it was so bothersome, but it's nice that his mom lets him use the kitchen for his reviews.

tony's picture

Hello,
I did go and have a look,
I did get a kick like you predicted,
I'll give you a thumb up,
thanks.
Tony in Michigan
Tony in Michigan

jeckyll's picture

I'd commented previous how it's important to know the reviewers bias (maybe especially for them) and also their preferences. In this case, I believe I like similar sounding headphones to Tyll. I bought a pair of HP50's after reading the review here and like them a bunch.

The read the pono review, which answers a lot of the key questions like:
Is there a huge difference? No
Is there a reason to buy it? Yes (depending on your use)
Why would I enjoy it? Because it's going to suck you in emotionally (in a good way)
etc. etc.
And also because it clearly breaks out the analytical and emotional differences.

That's what's been missing for me with all the other 'pono-noise'.

Will I buy one based on this review? No. Because my at-home listening time has been greatly reduced lately, and I don't think I'd want to drag the player around with me at the gym or around town. I'm listening more in environments where I use music to drown out external noise and do work or focus on other things.

However, if that changes and I actually look for a play for the pure joy of listening, I'd really consider picking one up.

Thanks Tyll, really enjoyed the review.

Masltr's picture

Tyll,

Thanks for the review. I'm currently on prolonged overseas trip and set goal for myself to use some hotel downtime to do the exact test you did.

I tested the iPhone 5, ak100 mkI, and pono player. Tested mostly mostly CDs ripped to flac. For me iPhone sounded very digital. Aka and pono sounded more musical with slightly more depth of soundstage to pono player.

I used UERM in ear monitors and didn't notice an obvious failing that your article suggests should occur. It may be there, but not noticeable. Daily wear IEMs are the jha13fp you used as well, but I have balanced cable. This is my preferred combination.

Perhaps most telling fact vote for pono is I have left my ak240 home on this trip as I actually find it lacks bottom end signal - though understand this May be due to poor match with my headphones.

Long winded way to ask is there an IEM that does work well with Pono? Suppose I could sort through your charts, but hoping you have had same thoughts.

Thx again!

Tyll Hertsens's picture
I also mention the Philips S1 as a good choice. Basically, one way around the problem is to look for dynamic driver IEMs---they won't have the same wildly swinging impedance that BAIEMs have.
Chrisg2229's picture

I am listening to one of Charles' converters right now (QB-9 DSD) and I assure you it sounds grand! you need to give one a listen.

Chrisg2229 (aka 7ryder @head-fi)

tony's picture

thanks for passing that along, the Ayre stuff looks to be impressive, I'll keep an eye out for a chance to have a good listen.

Tony in Michigan

lachlanlikesathing's picture

Hey Tyll, a really great and upfront review! I have done the whole switching box thing and it is tremendously exhausting, so props to you for setting up in so many combinations.

I was hoping I could get some clarification on your testing methodology because I'm trying to do something similar when testing the Geek Pulse amp/DAC.

"I did about six hours of blind testing over the course of three days testing the Pono against a variety of other sources, and sometimes with various headphones. Sessions usually proceeded like this: First attempt with new devices would start me getting familiar with the new sounds. I would often misidentify the Pono in the first test. Second test would be about 50/50 getting the Pono right. Usually by the third test I would be able to rightly identify the Pono Player and by the fourth test could identify all three players and would generally get it right four out of five times thereafter."

I'm a little confused about that last past. From your description, you mean that one 'test' is testing with the 3 devices and one particular cable routing configuration. Then do you scramble the cables after each test? Or are you doing 4+ tests on the same cable configuration?

I'm assuming you scrambled the cables, which means that if there was NO audible difference between the players (null hypothesis), you would guess which one was the Pono correctly 33% of the time. Do you know how many times you would have to pick the Pono correctly be statistically confident that you weren't picking out the Pono by guessing? I know for an A/B trial it would have to be 4/5 to get a 0.95 probability that you didn't pick it out by random chance, but for the A/B/C trial how many times would you have to pick correctly?

In your description you suggest that in a typical trial you would pick the Pono incorrectly the first time (0/1), then 50/50 pick the Pono the second time (1/2 or 0/2), then 'usually' by the third test pick it correctly (2/3 or 1/3), then pick it correctly thereafter. (4/5 or 3/5) Honestly I think it may have been better if you just published your raw results because your description is a bit ambiguous. Though again it's great that you even went to the trouble of doing the switching box thing, because I know it's intensely frustrating and tedious.

Obviously there is a difference in sound between the players, and what your review seems to suggest is that the difference in output impedances can account for some of these differences. But I'd been interested to know how much of the difference between the players can be attributed to that difference in output impedances, and how much can be attributed to other internal hardware differences. It would be interesting to know how easily you could pick the Pono apart from the Note 4 and iPad Air, and HOW much easier it was statistically for you to do that versus picking out the Pono against the other kilobuck players.

It's also a shame that you didn't test any high resolution files.

I'm no hardware engineer but I've been doing some reading about digital filters (including Ayre's own documentation) after getting this Geek Pulse which has a choice of minimum phase or linear phase ('brick-wall') filtering.

As I understand it, even playing a 44kHz file through a DAC that has a higher internal sampling rate allows it to oversample and reduce the introduction of time smearing or phase shifting in the audible spectrum on the hardware side - depending on how you design the filter.

Hansen's comments seem somewhat misleading. "a) Brickwall filtering creates massive time smear. b) The human ear/brain is already known to be exquisitely sensitive to time smear. c) DBT and AB/X are really only sensitive to differences in frequency response. Using these tools for anything to do with music is like pounding a nail with a screwdriver. Ain't gonna work."

Sure, human beings are sensitive to time smear. But I don't think that anyone has actually demonstrated conclusively that human beings are sensitive to the quantity of time smear introduced by the one iteration of 'brick wall' (linear phase) filtering introduced in the hardware stage. If the human ear/brain is 'exquisitely sensitive' to this time smear, this should either show up in an ABX or some other experimental design. Hansen's comments seem to imply that human beings can perceive this time smearing in ways that do not show up in an ABX test. But if he can't point to what these 'other ways' are, then it's an unproven assertion. I've not seen any results that indicate that different digital filters are subjectively distinguishable. The Stereophile article I could find on the topic suggested the opposite:

"If energy smear is a real and significant effect, then these seven very different filters should have made obviously different imprints on the sound quality of the test tracks. But the listening results, described in the sidebar, indicate that the sonic disparities between the filtered tracks and the 24/96 originals were very difficult to pin down. Only Filter 4, the maximum-phase filter in which all the ringing is pre-ringing, introduced degradation that the listeners felt confident in identifying. It seems that energy smear, supposedly a bête noir of digital audio, seems surprisingly reluctant to show its face."

http://www.stereophile.com/content/ringing-false-digital-audios-ubiquito...

What's funny about this assertion is that other filter designs like minimum phase filtering introduce phase shifting, and you could just as easily argue that the "human ear/brain is already known to be exquisitely sensitive to phase shifting."

Regardless of how you design the filter, it's likely by the time you have the file in your hands (so to speak) it's already gone through many digital filtering stages. The time smearing or phase shifting introduced on the mastering and recording side is baked right into the file and I'm not sure it can be removed in hardware. (Again I could be wrong here, there may be some hardware wizadry that can compensate for it.) If the human ear is 'exquisitely sensitive' to the problems introduced by digital filtering, then obviously the problem is much more serious in the recording / mastering stage - how many cycles of pre-ringing are introduced there?

So the interesting thing would be to get a high resolution recording, and then do the final 44kHz conversion / filtering yourself. You could see how audible the difference is with this one iteration of filtering (the conversion from the master to 44kHz) really is.

Charles Hansen's picture

Hi Lachlan,

Just a couple of quick points in response to your very detailed and thorough post:

1) No, oversampling a 44.1 kHz source does not allow one to use gentler filter slopes.

All that oversampling does is move the burden from the analog domain to the digital domain. When digital was first introduced, all of the filtering was done with analog. Building a 9-pole or 11-pole elliptic analog filter is a real bear -- extremely twitchy and demanding super close tolerance parts.

As CMOS technology matured, it became easier and cheaper to create digital filters than analog filters. All that oversampling does is move the filtering from the analog side to the digital side.

But there is no free lunch...

It doesn't matter whether a filter is analog or digital -- the steeper the filter and the sharper the "knee", the more it will ring when hit with a transient, creating time smear.

2) The reason that the ear/brain evolved to be so sensitive to time smear is because that is how we localize sounds in 3D space. Being able to pin-point the location of a dry leaf being crushed by a stalking tiger conferred a massive survival advantage.

Frequency response is almost tertiary in its importance. Anybody can recognize a familiar voice on a telephone with a bandwidth of 300 Hz to 3 kHz, even if you haven't seen that person in twenty years. (So much for the argument about the "short persistence" of aural memory...)

If you want to play around with different filters, all of the Ayre digital products have a switch on the rear panel that allows the user to select between frequency optimized filters ("Measure", with more ringing and time smear) or time-domain optimized filters ("Listen", with far less ringing and time smear).

It's best to listen for yourself, but you can also read the reviews of our products. I can't think of a single instance when a reviewer preferred the sound of the "Measure" position.

Hope this helps,
Charles Hansen

lachlanlikesathing's picture

Thanks for the comment Charles!

1) As I understood it, having the DAC oversample the file internally allowed you to use gentler filters. As Monty from Xiph.org puts it,

"That's only half the story. Because digital filters have few of the practical limitations of an analog filter, we can complete the anti-aliasing process with greater efficiency and precision digitally. The very high rate raw digital signal passes through a digital anti-aliasing filter, which has no trouble fitting a transition band into a tight space. After this further digital anti-aliasing, the extra padding samples are simply thrown away. Oversampled playback approximately works in reverse.

This means we can use low rate 44.1kHz or 48kHz audio with all the fidelity benefits of 192kHz or higher sampling (smooth frequency response, low aliasing) and none of the drawbacks (ultrasonics that cause intermodulation distortion, wasted space). Nearly all of today's analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) oversample at very high rates. Few people realize this is happening because it's completely automatic and hidden."

http://people.xiph.org/~xiphmont/demo/neil-young.html

Now again I'm no audio engineer so I only have your word and Monty's, and both of you seem to be saying different things. I doubt there is any way that you can really explain this to me when I don't fundamentally understand the mathematics, but I'd appreciate your explanation.

2) I'm sure human beings are sensitive to time smear and if you introduced a lot of time smear it would be something people pick up. The question is whether or not people are sensitive to the different amounts of pre ringing in a well designed minimum phase filter versus a well designed linear phase filter - or for that matter, things like phase distortion introduced by filters. I'm sure you've spent a lot of engineering effort in eliminating pre-ringing, but the question is - is this actually perceptible versus say a consumer grade audio device that implements a 'good enough' linear phase filter (like most Apple devices?) Furthermore is it even salient when there's probably a great deal of time smear or otherwise being introduced in the mastering stage?

It's all well and good to say that your customers and reviewers don't seem to like the 'measure' filter, but you've already made it distinguishable for them by calling it the 'measure' filter. There's already a lot of psychological loading when you tell someone one filter is meant to sound more musical and the other is meant to sound more analytical. I have not come across properly conducted blind tests that suggest a minimum phase filter is audibly different from a linear phase filter, or one that even demonstrates it is subjectively preferred.

On my Geek Pulse it lets me choose between a linear phase filter and a minimum phase filter, and honestly I would be lying if I said I could really hear a difference between the two.

Again I'm not suggesting there is no measurable difference between the two. My line of questioning just comes out of a lot of marketing that suggests the differences are and immediately noticeable, when there doesn't see to be any evidence of that being true. Descriptions like "massive time smear" and "exquisitely sensitive" seem to me to be a little exagerrated to me when I can't find much objective evidence to support them.

Charles Hansen's picture

Nice comments and well spoken. For me, Xiph has very little to expand my knowledge base. YMMV. I've read his writings, but not for years.

As far as "objective evidence to support", I lost interest in that decades ago. I experience what I experience. I trust those experiences and rely on them. I don't spend time looking to others to validate my experiences. Again, YMMV.

Have a pleasant journey on your audio and musical explorations!

Charles Hansen

ultrabike's picture

1) While it is true that oversampling moves the burden of analog reconstruction filtering to the digital part, it is IMO not true that all digital filters that brickwall mess up and produce a problematic "time smear".

A large brickwall linear phase filter might produce some transients and delay. But once in steady state (as in when the music start playing), these issues go away. A minimum phase filter has more issues to contend with as frequencies are not delayed by the same amount as is the case for linear phase filter.

The lack of a free lunch here lies on the fact that an appropriate FIR linear phase filter will be fairly large and resource consuming, unlike say an elliptic IIR filter (digital or analog).

2) The way "time smear" is vaguely defined here seems to correspond to the Gibbs phenomenon where an abrupt change from passband to stopband gives rise to "ringing". If the transition from passband to stopband is above the audible region, AFAIK there is little (and perhaps no) evidence to support that such "time smear" contributes to localization of sounds in 3-D space, and plays a role in finding a leaf being crushed by a staking panda bear.

3) While perhaps not the one thing that explains everything, frequency response is of great importance in audio characterization. Furthermore, voice through a 300 Hz to 3 kHz filter (as found in analog phone filters), will get distorted obviously so. Depending on the pitch and tone of the persons voice, even when familiar with that person, one may miss identify who is on the other line. My wife and her sister have different voices, however on the phone they sounded pretty close and they used to play pranks because of this to plenty of folks.

4) Heard the Pono. Liked the sound, but it was a bit too warm and slow IMO.

Charles Hansen's picture

I suppose that we could enter into endless discussions on the theory of filters (digital and otherwise). But in the end, the player is the player and it sounds the way it sounds.

So for me the relevant point was your final one. You listened to it and it wasn't for you. That's fine, as there are a lot of choices available. Pono is offering a different one than anything that's come before. Many people (including Tyll) like it, but no product will be right for everybody. Can you imagine if there were only one "best" car on the market?

Cheers,
Charles Hansen

ultrabike's picture

While I disagree with your "time smear" discussions, and feel some aspects of digital and analog signal processing are not that loosely defined or controversial, I agree with you that the performance perception of the Pono product is what is most relevant as far as the Pono product itself is concerned.

The warmth and slowness I perceived relative to other stuff is not necessarily a bad thing IMO. It all depends on what one is looking for. Furthermore, I do know some folks that absolutely love the sound of your product. The main complain I would have about it relates to it's built and perhaps options. I know perhaps quite a bit of the effort went into the sound, but perhaps having an special aluminum body edition with choice of colors might be nice. Perhaps adding a choice for digital filters would be cool.

Other than that, IMO this is a great player in a very competitive market. I also feel Tyll did an awesome job in covering it.

Charles Hansen's picture

Great comments and completely agree, especially regarding your assessment of Tyll's review! Your suggestions are good ones although not necessarily practical ones.

Over the years, I have learned that it is literally impossible to be all things to all people. It can be boiled down to "Performance, features, price -- pick any two."

Also at Ayre we strongly believe in not offering options. Instead we prefer to keep the operation of the product as simple as possible so that non-audiophiles and non-technical people are not overwhelmed with choices that are incomprehensible to them. We spend dozens of hours performing the listening tests so that you won't have to.

We violated our own rule by adding the "Listen/Measure" switch, as at the time that the CX-7 CD player was introduced, the audiophile press virtually crucified a player that only offered the "slow-rolloff" option. We felt forced to include the switch, but completely de-emphasized it by moving it to the rear panel where it is difficult to access.

It is absolutely not meant to be a feature that is fiddled with from album-to-album or song-to-song. Instead it is there to be set once and forget it. In the owner's manual we recommend using only the "Listen" setting and only use the "Measure" setting if required for a particular situation.

All future Ayre products will likely omit this choice, with the first example (after the PonoPlayer itself) being our new Codex DAC + headphone amp + preamp that is being debuted at the ongoing Can-Jam. Too many choices leads to too much confusion. We build our products for customers who just want to press "Play" and get lost in the music. Other customers want the choices, and there are many, many other brands that offer it to them. Ayre doesn't (see the first paragraph).

There will be a more detailed response regarding the industrial design of the player coming from Phil Baker, SVP of Product Development and Operations at Pono in the next couple of days. This should provide some great insight into the industrial design decisions that were made.

Joe Bloggs's picture

In order to be bothered by the supposed "time smear" one needs to actually be able to hear it. Linked below is an illustration of a worst case of an instantaneous impulse brickwall filtered below 22.05kHz:
https://1drv.ms/i/s!AtuiwfIBRYFEhmdSiWVnBZsMRXAq

The ringing ("time smear as you put it") goes on and on, but as the spectrogram shows, the smearing is exclusively limited to frequencies above 20kHz.

How much audible content is there above 20kHz in the case of hi-res audio, let alone 44.1kHz sampled CDs? Let me be generous and take a sample track at 96kHz as an example:
https://1drv.ms/u/s!AtuiwfIBRYFEhmbNWbPGsAH0CmKL

What is the potential for audible ringing in this track if downsampled to 44.1kHz? In the following track a brickwall filter has been applied filtering out all frequencies BELOW 20kHz.
https://1drv.ms/u/s!AtuiwfIBRYFEhmW1UAqbwE84ZeD5

You're invited to play the first track as loud as you can possibly bear and then play the second track at the same volume--and I challenge you to hear anything out of it.

Tyll Hertsens's picture
I'm at CanJam SoCal so I really can't give you the answer your deserve. Lemme give you the short version, Lachlan: As a press dude---like you---I really can't afford the time for complex testing. That's the purview of folks like Harman and such. Folks like you and I can only, as best we can, criticize the folks who can afford to do the hard work. It's a patently unfair arrangement in some ways...and perfectly fair in others. We are the surrogate consumer, and you and I are picky bastards. You and I should just keep doing the best we can. In fact, you being younger and more full of spunk should be out to kick my ass.

Get on it, mate.

FWIW, InnerFidelity readers, keep track of Lachlanlikesathing, good stuff.

lachlanlikesathing's picture

I hear you Tyll. I seriously don't mean to snipe at you about not doing a good enough blind test when you very clearly make the argument for both blind testing and volume matching, which is already more effort than what most reviewers will approaching these kinds of topics. I've honestly been sitting here for months trying to work out how to properly self administer a blind trial in a way that would be consistent and also not exhausting. Scrambling the cables actually seems like a great idea. The annoying thing is that if you have to scramble the cables after every test, then doing something like 10 tests becomes very trying.

If only there was some kind of magic ABX box which would randomly route two inputs to an output, so that the scambling was automated.

Tyll Hertsens's picture
Just to answer that one, yes, I did scramble the cables after every test. I thought about making a little movie of me doing the tests, or a test, but it would have been like watching paint dry.
deckeda's picture

Please also note that Tyll's blind eval was incorporated in the service of a subjective result. Or at least, led to that, i.e. the enjoyment of music.

While I'd encourage you to follow whatever objective path helps you best, there's a very strong and salient reason why Mr. Hansen said what he said about Xiph.org (and by extension, Monty's writing ... Monty's vested interest in Ogg and so on. I'm not nearly so charitable nor polite, so will refrain from further comment about anything Xiph related.)

acs's picture

Great review. I appreciate your taking the time to do a blind comparison, to be both objective and subjective. This is difficult to balance, and most reviewers would not be a capable of delivering this kind of review. Your acknowledgement of the validity of both subjective and objective analysis makes you a diamond among reviewers.

I have selfish reasons for being curious about how the Fiio X5 fared in that I own one and do not have the other players on hand to compare, so I am curious about your thoughts regarding it in the context of this review.

Perhaps you had reasons for leaving the Fiio out of the review that are still valid and you won't be able to respond, and if that is the case, then please do as you must, but if it was an oversight, or a length/time issue, it would be appreciated if you were willing to take a moment to share your listening experience (objective and subjective) regarding the X5, as you did with the other players that were mentioned in the article.

Thank you again for all that you have done to contribute to this hobby. I have learned a great deal from following you over the years.

Torpedo's picture

this comment of yours, Tyll, describes how I've felt so many times:
"In my experience there are two ways to go about blind testing: objective evaluation and subjective experiencing. In objective evaluation you try to listen carefully for differences in the signal you are hearing. With subjective experiencing you don't evaluate the music but rather evaluate your experience while you are listening for enjoyment. The problem with objective evaluation is that you may end up knowing what sounds different between each player, but you'll usually not have a clear idea which you'd actually prefer. And the problem with subjective experiencing is you might know which you prefer, but you are likely not going to know why. It's kind of like the Heisenberg uncertainty principle: you can know where something is or how fast it's moving, but you can't know both simultaneously."
IMO you have both at some point when the objective difference that you can recognise pops out in your brains. The more subtle that difference (or bunch of them) the more time and attention your brain needs to realise it.
Thank you very much for this thorough and well written review. I haven't made any blind testing myself with the Pono, these days I rely more on long term coexistence. The Pono is a good device to enjoy music on the go when afar the "big" systems. Fun and enticing, which is what one really needs.

I didn't know the Pono can be configured for balanced headphone output. I need to learn to read the marketing literature more deeply. I liked how it handles the HD600, but on balanced things will be better for sure. Time to investigate...

Charles Hansen's picture

As noted in my Manufacturer's Comment, I've a pair of Sennheiser HD-600's myself. Running single-ended, full volume is just loud enough for loud listening. That is because the standard output voltage for portable players is only 1 volt RMS.

The HD-600's are 300 ohm cans, and require more voltage to drive. All of the "newer" earphones that are designed to work with portable players have much lower impedances, normally between 15 and 30 ohms, to get more power from the low-voltage signal. Often the connector is a give-away. A 1/4" plug will typically indicate a high impedance headphone, while a 3.5 mm plug is surely designed for portable use and will be low impedance. Of course there are always exceptions. (Tyll will know much more than myself on this topic.)

The great thing about the HD-600's is how easy it is to convert them to balanced. If you're not a tinkerer, just purchase some upgrade cables and plug them in. It will sound better for two reasons -- better wire and balanced operation. If you know how to solder, it is easy to cut off the 1/4" plug and replace it with two 3.5 mm plugs for balanced operation. Have fun!

Torpedo's picture

very much for your kind comment, Mr Hansen. I've used my HD600 balanced from a couple of balanced headphone amps I own. However they use the old fashioned XLR (3 pins, 1 connector per channel) connectors. I think I could make a wire to use them balanced from the Pono, but I'd need to know if the mini-jack connections used are
- TRS or TRSS as someone else claimed on a review at another website (which doesn't match the pics I've seen at Cardas and other sites).
- The pins for hot and cold are T and R or T-S or R-S.

I think I'll be able to guess what jack makes for each channel hehehe.

I read your explanation and totally makes sense to me. The HD600 benefit from balanced use even from quite beefy amps, so the difference must be huge when the output voltage is limited to 1V.

Charles Hansen's picture

Hi Torpedo,

Yes, the one thing that I disagreed with Tyll about was his choice of connectors for balanced headphones. He was the first and therefore set the standard for many years.

The problem with two separate XLRs are multiple. On the headphone side, they are ungainly being both large and heavy. On the amp (player) side, they take up a massive amount of panel space.

Recently some manufacturers have tried shifting away from that, so we see either a single 4-pin XLR or Mini-XLR's or both. The 4-pin XLR is still massive and space hungry. The Mini-XLR's aren't really a standard product as the only manufacturer of them is Switchcraft.

With the PonoPlayer we were forced to use two 3.5 mm jacks as the industrial design was long since locked down before I developed the audio circuitry. But I think it ended up being the best possible solution:

1) The headphones now have two mini-plugs, which are very light and very small.

2) The panel space required on an amp (player) is minimal.

As there are around 30,000 PonoPlayers in the world today, two 3.5 mm mini jacks/plugs IS the new standard! That is far more than the combined output of every single specialty manufacturer that has ever made balanced headphone amps...

This fact is reflected in Ayre's new USB DAC + headphone amp + preamp, the Codex. The front panel has two 3.5 mm jacks exactly like the PonoPlayer and can be configured for either driving a single pair of balanced headphonse or two pair of single-ended headphones.

I think that within five years every balanced headphone amp (player) will use this configuration. It makes far more sense than anything else on the market in my opinion. YMMV.

Regarding the PonoPlayer the relevant schematics have been compiled on to what they call "Tech Sheet 03" which can be found at:

https://ponomusic.force.com/servlet/fileField?id=0BEA0000000GoCT

You may need to sign in as a member of the PonoForum to access this URL, I'm not sure...

The best thing to do is to join the PonoForum (www.ponomusic.com), click on the yellow rectangle with "Pono Community". Then at the top of your screen you will see a black bar. There is the word "Community" towards the left side with a drop-down arrow. Click on that and scroll down to "Knowledge" and click again.

You will see a list of "Tech Sheets". 01, 02, and 03 explain the balanced mode operation of the Pono in great detail. Let me know if you have any questions after that.

Torpedo's picture

Thanks again, Mr Hansen. The articles are certainly a bit hidden into the--not ver friendly--Pono's website structure, but are clear, the diagrams confirm what I was guessing. I think that converting a standard HD600 or 650 cable into a balanced Pono one should be pretty straightforward.
I agree, the use of two big Cannon connectors for balanced headphone use didn't make much sense, specially considering that for safety reasons they go against the convention of using the male connector for the output. Usually quite inconvenient if trying to convert standard cables for headphone use.
Kind regards

castleofargh's picture

The rapid layman way you give to estimate the needs for the pono is at the very least a strangely vague approach from you(is it your attempt at making things simple, or does that come from pono telling you to shut up about power output?) Because I can't get why you would go to such a length to deliver some matter of intel to us, while not going for the real thing. Like... max power into a few loads.

I can understand that all the marketing campaign was a great success of abuses and misdirections to create a buzz. But now the DAP is out, and to know what it can drive, the very best we can find is your voltage at 90db thing. And that's not even so much out of the ordinary for DAPs! The audio world is a mess.

Many "audiophiles" are thrilled to read about no feedback loop or discrete stuff, and in some ways I feel privileged to be able to read Charles posts.
But call me dream killer, what I'm interested in is the actual signal that gets out of the box. I don't care how it's built, I don't care if there is a magic rock shaped like Jesus inside the toblerone. If we're talking about the sound quality, and pono dudes have hammered that into us for 2 loooong years. There are only 2 things that should matter.

1/ can it drive my cans?
2/does the output measure good into a lod similar to my headphone?
The rest you can keep.
a few measurements into 16/32/150ohm and the impedance output, that's all I've been asking for. The very basic stuff anything with an amp section should be required by law to provide IMO. I can read how much salt is in a can of tomatoes, but I can't find out if a source I want to buy for my headphone can drive it loud enough to reach 105 or 110db peaks without massive distortion. it's the first thing I really need to know when buying a source!
How messed up is that?
We almost never see a DAC or an amp without specs. But if it's a DAP that has both of them in one box, suddenly stuff are subjective? WTF? No they're not! Specs are just usually so bad that most manufacturers don't dare to show them(for that congrats to FIIO for trying).
Can it drive your headphone? Well that just seems to be another of those not so important stuff(like impedance and FR^_^). Instead let's talk about how we solved that stuff at 22khz we were all so scared about on music that has almost no content after 15khz, using headphones that will most likely output that freq at -60db straight into my ears that can't detect past 17khz full scale. That's obviously the real concern here, I'm so silly.

So thank you Tyll for not totally avoiding the problem and trying to provide some matter of idea about what headphone to use. Still the audio world really needs some regulations as obviously manufacturers will never play fair on their own.

Charles Hansen's picture

Tyll didn't have to measure the PonoPlayer as John Atkinson already had in his review for Stereophile:

www.stereophile.com/content/pono-ponoplayer-portable-music-player

You should be able to find what you are looking for in the "Measurements" section. Hope this helps.

castleofargh's picture

Well no it doesn't really. I feel like I'm being told about the options in the GPS of a car(that's interesting at some point, but most stuff are measured with "no load". so not real usage.), but when I ask about the engine or fuel consumption, it's impossible to know. I'm really asking for the most basic stuff here. And those stuff should come from the manufacturer, it's not normal to have to chase after them.

I mean when you make an amplifier for speakers you will give max power output into 4 and 8ohm right? We wouldn't have to wait for reviews to learn about it piece by piece.

For a DAC I would expect the max voltage to set my gain on the amp, some noise floor and crosstalk wouldn't kill me.

When doing a headphone amplifier, the manufacturer will provide max power into usually 16/32/ and another one at 150/300or even 600ohm(all that usually for 1%THD). They wouldn't go “just listen”.

So why don't we get those stuff for a DAP?
Again I whine more in general than on Pono alone. It so happens that it angers me more than usual not to see specs for a product that lobotomized us for 2years with high fidelity, high resolution and professional approach of music. Yeah sure professionals that won't tell you if you can drive your headphone and ask you to just try it. Seems legit...
guys like FIIO who don't pretend to do amazing stuff, will publish basic specs pretty truthfully for each product they get out. So how come so many “audiophile” high res DAPs hide those specs like it's the murder weapon? (the ideas that come to mind aren't good for your guys, I can tell you that much).

I got the almost 1V (into what load?) From stereophile, from Tyll strange tuto about his 0.1v@90db for single ended headphone I was guessing between 1v and 1.8v (to reach peaks at 110 or 115db). But I'm still just making conjectures when stuff like max voltage or max power should be printed at the back of the DAP.

Charles Hansen's picture

Hi Castle,

First of all if you look at Ayre's literature, we publish very few specifications. We tell the dimensions so that you can see if it will fit in your rack. We tell the weight so you will know if you need a friend to help you unpack it. We tell the input impedance to make sure that it will be compatible with your other equipment.

But when it comes to electrical specs, we are like Bose -- virtually nothing. The reason is that it has virtually nothing to do with sound quality.

For our power amps we do publish a power output specification, but that is only because the world of loudspeakers is really quite standardized. Everything is essentially either 4 ohms or 8 ohms and that is it.

In the world of headphones there are NO standards whatsoever. Things range from a few ohms to a few hundred ohms with no rhyme or reason other than the fact that 'phones designed for portable players will typically be under 50 ohms.

Since there is no standard load, there is no standard way to test. If you know enough to care, you should also know enough to simply apply Ohm's law and calculate the output power in two seconds.

If you want to know how it varies with load impedance, simply draw the equivalent circuit with an amplifier output of 3 ohms (that is close enough for all practical purposes) and you will be able to calculate the output power in ten seconds.

That still will tell you absolutely nothing about how the PonoPlayer will sound with a given pair of headphones.

It is analogous to the situation of modifying a Toyota Prius. If you doubled the power of the electric motors, would the 0 - 60 time drop significantly? Almost certainly not! All that would happen is that you would spin the front wheels upon launch and very little of that extra power would actually get to the ground.

One would have to almost re-design the entire car to take advantage of the doubled power. So knowing the power of the motor by itself tells you almost nothing. Same thing with a headphone amplifier. There are a thousand other factors that will impact the sound quality.

Hope this is a bit clearer.

Thanks,
Charles Hansen

Charles Hansen's picture

Hi Castle,

I believe that Stereophile measure the output voltage into the 100 kohm input impedance of the Audio Precision test set, so essentially an open circuit.

I could walk you through how to calculate the power into a given load, taking into account the output impedance of the amplifier, but I choose not to for two reasons:

1) This comment section is not the place for free tutorials in electrical engineering. There are other websites for that.

2) Doing so would simply emphasize the numbers. As noted previously, there is essentially zero correlation between the measurements and perceived sound quality. I actively discourage paying any attention to the measurements whatsoever, especially with electronics. It does far more harm than good.

With transducers it can be helpful, but only to a trained expert. Search out Tyll's test of the $2 headphones sold by United Airlines for in-flight entertainment. They measured abysmally in every respect, yet after he listened to them he stated that they didn't sound nearly as bad as they measured.

The bottom line is that people will purchase a DAP for one reason only -- to listen to it. Nobody is buying it to take it home and measure it with test equipment. Why would anybody test anything except in the manner in which it will actually be used?

It would be like testing screwdrivers by measuring how quickly one could pound nails with them. When it comes to a screwdriver, one of the most important things in actual use is how comfortable the handle is in your hands when applying high torque. How in the world could anybody measure that?

Again, I'm not trying to be obtuse or stubborn. I'm honestly trying to convey the knowledge I've gained in over two decades of designing high-performance electronics and another decade of designing high performance loudspeakers (I was the founder of Avalon Acoustics.)

Hope this helps to clarify things a bit. Happy listening!

Charles Hansen

ultrabike's picture

"I could walk you through how to calculate the power into a given load, taking into account the output impedance of the amplifier, but I choose not to for two reasons:

1) This comment section is not the place for free tutorials in electrical engineering. There are other websites for that."

It may be me, but that's proly a lot simpler to explain than the diamon buffer comprised of a pair of complementary emitter followers driving a second cross-coupled pair of complementary emitter follower deal in the commentary section.

"2) Doing so would simply emphasize the numbers. As noted previously, there is essentially zero correlation between the measurements and perceived sound quality. I actively discourage paying any attention to the measurements whatsoever, especially with electronics. It does far more harm than good."

Completely disagree with this. How do you guys design your products then? You guys use the quija to get pcb traces right? Ask Martha Steward about what caps and resistor trend best with the chassis colors? While measurements are not the end story and field tests are IMO a requirement. I don't see how guys avoid using measurements and development equipment to come up with your products. Such measurements should somehow correlate to fielded perfromance.

"With transducers it can be helpful, but only to a trained expert. Search out Tyll's test of the $2 headphones sold by United Airlines for in-flight entertainment. They measured abysmally in every respect, yet after he listened to them he stated that they didn't sound nearly as bad as they measured."

Heard and measured plane headphones. They sounded like they measured: Like shit.

"The bottom line is that people will purchase a DAP for one reason only -- to listen to it. Nobody is buying it to take it home and measure it with test equipment. Why would anybody test anything except in the manner in which it will actually be used?"

I purchase a DAP to listen to it. But usually DAPs that measure horrible sound horrible. Not sure what's this discussion about using DAPs to measure though.

"It would be like testing screwdrivers by measuring how quickly one could pound nails with them. When it comes to a screwdriver, one of the most important things in actual use is how comfortable the handle is in your hands when applying high torque. How in the world could anybody measure that?"

An AP to me is like a hammer pounding nails. Not sure what you are trying to get at here.

"I'm honestly trying to convey the knowledge I've gained in over two decades of designing high-performance electronics and another decade of designing high performance loudspeakers"

Not trying to be a pain in the ass, but likely you learned through all those years the value that audio characterization brings to table. I mean, you most have used such stuffs given you know the output impedance, frequency response, drive, topology and stuffs of your product, so not sure why you seem to be putting characterization down.

Charles Hansen's picture

Hi Ultrabike,

1) Take a theoretically perfect AC generator outputting 1 volt RMS and add a 3 ohm resistor in series. With a very high (negligible) load such as the 100 kohm input impedance of an AP test set, the 3 ohms pales to insignificance and you will measure 1 volt X (100,000/100,003) = 0.99997 volts RMS.

Now repeat this with a 32 ohm load and the equation is 1 volt X {32/(32+3)} = 0.914 volts. Since P = E^2/R we get an output power into 32 ohms of 26 mW.

I will leave to you to calculate the output power into other impedances.

Now, what have we learned? I say absolutely zero about the PonoPlayer.

a) It stills sounds exactly the same as it did before I made this post and how it actually sounds is the only thing that the user can experience.

b) Now you know how to calculate the output power of any amplifier if you know the output voltage, the output impedance, and the load impedance (which you already did). As noted in my previous post, an internet search would have saved me a lot of time and Tyll's comment section a lot of space.

2) No, we don't use a Ouija board to select components. I know of no measurements that will tell you which ones sound good. The only way to know how they will affect the sound of a design is to listen to them.

At Ayre we have spent years devising different listening tests for different components. Switching devices are relatively easy, resistors are a bit trickier, capacitors more difficult still. But it is our job. We take it seriously and spend hundreds (if not thousands) of man-hours doing listening tests on any particular type of component to find the best sounding ones. As they say, "If it were easy, everyone would do it".

Then the customer gets to simply press "Play", sit back and enjoy the music. There are some wonderful stories about how we do these tests and the truth is that Ayre has not historically done a very good job of telling them. But telling them here would be advertising and inappropriate.

(You didn't continue numbering after this, but I will.)

3) Tyll said in his review that the headphones sounded horrible. When he measured them they measured "abysmally", even worse than he expected. After measuring, he listened again and said that they didn't sound as bad as the measurements would have led him to expect.

The point is that Tyll has been trying to correlate measurements with sound quality in transducers for many, many years and can still only make generalized correlations, not specific ones.

I've been trying for decades to find any correlation between measurements and sound quality in electronics. Zero. If you can do better, please feel free. I'm sure that I am not the smartest person on the entire planet.

4) John Atkinson said that the PonoPlayer measured "very well". Why would you expect it to sound any differently?

5) Why would you expect an Audio Precision distortion analyzer to be able to tell you how anything sounds?

6) I've heard incredible sound from 3 watt single-ended triode power amps with several percentage points of distortion at rated power. I've also heard incredible sound from solid-state designs with zero feedback and less than 0.01% distortion had rated power. I've never heard incredible sound from a solid-state design with high amounts of feedback.

I know of no measurement that will definitively tell me if a solid-state design uses feedback or not, nor how much it uses. I've been around and around trying to find measurements that correlate to sound quality. I've not found any. I don't know of anybody who claims to either. If you do, please let us know and we can investigate.

In my experience there are two types of audiophiles -- those who have learned to trust their own senses and those who haven't. The latter are constantly looking for some measurement or some review to validate their purchasing decisions.

My further experience is that eventually all of the second category will eventually shift into the first category, given enough time and enough experience. Normally there is some sort of "moment of epiphany" that creates this shift.

I consider myself very fortunate as I experienced this shift at a very early age. As a teenager working in the repair department at one of the very first "high-end" shops in the country, I was confident that all well designed (say) preamplifiers sounded exactly the same.

After all "High Fidelity" and "Stereo Review" tested them on the bench and everything would have a frequency response within ±0.1 dB from 20 Hz to 20 kHz, and the distortion at any output level required to clip a power amplifier was below 0.01% at any audible frequency as well. I convinced myself that therefore they would all sound identical.

I made friends with the manager of another shop, a gentleman older and much wiser than myself (Hi, CDR!). He had an Audio Research SP-3 tube-type preamp in his home system, and invited me over to perform a preamp comparison test. He brought a Dyna PAT-5 and something else I don't recall from his store, and I brought an API preamp (I don't recall the model but I remember their ad slogan -- "It's not what's up front that counts. It's what comes out of the back, Jack" or similar) and another solid-state preamp, probably a McIntosh.

Back then the only source was LP and nobody had moving coil phono cartridges. All preamps had built-in phono stages (with RIAA equalization accuracy within ± 0.25 dB). When we sat down to listen, I was absolutely gobsmacked.

Not only did the four solid-state preamps sound completely different from one another, but the Audio Research SP-3 was clearly on a completely different level. It was nearly impossible to for oneself to listen to the other preamps after hearing how much better the Audio Research was. After that experience I learned that measurements are not to be trusted -- only the ears.

When you purchase a bottle of wine, do you want to know the alcohol content, the acidity, the tartness and so on, all quantified in numbers before you buy it? Can you tell the difference between cheap steaks raised on a modern factory farm versus organic grass-fed beef versus the Japanese Kobe beef where the cows are fed beer and given daily massages, or do you want some sort of taste and texture measurement first? Do you insist on measurements when choosing what coffee or soft drink to consume? Would you be unable to distinguish your wife by holding her and kissing her lips and smelling her scent from any other woman in the world, without the aid of laboratory instruments?

I would guess confidently that the answer to all four questions is a resounding "No!" I am constantly puzzled by the fact that people treat their ears differently than all of their other senses.

Best regards,
Charles Hansen

ultrabike's picture

1) Unless we are talking about planar magnetic transducers and some well behaved dynamic ones, most things are not resistive. IEMs in particular can be a though load. Now considering your 1 Volt standard approach:

Shure SE530: http://www.innerfidelity.com/images/ShureSE530.pdf
At 100 Hz its about 25 ohms, so 32 mW at 100 Hz
At 5 kHz its about 10 ohms, so 59 mW at 5 kHz
At 20 kHz its about 40 ohms, so 21 mW at 20 kHz
we are looking at 2.6 and 4.7 dB differences relative to 5 kHz.

Now what have we learned?

That the Pono's 3 ohms output impedance is no go for certain cans.

a) Indeed, lots of IEMs may not work well here.
b) This was explained in Tyll's article.

2) Nobody is putting down listening tests. But before you get to the listening stage you obviously have to do some design work that involves measurements and engineering. Your ears tell you if something sounds awful, but your ears don't put together boards or design topologies to meet a specific design goal.

3) As far as the plane-phones, measurements are awful and they sound awful. What proly surprised some is that even with the awfulness we still are able to understand whats being "sung". Ears + brain can put together lots of stuff. But by the same token, ears + brain can tell fairly well that some stuff sounds off.

Here is an example where something measured poorly and sounded poorly:

http://www.changstar.com/index.php/topic,1308.0.html

Here is an example where something measured well and sounded well:

http://www.changstar.com/index.php/topic,1399.0.html

4) JA said the Pono measured "very well"... But he did pointed out quite a few flaws. And before I saw the measurements at all, those measured flaws might have explained my perception of it. I would say however that "flaw" is a pretty subjective word, just as "very well" is. Again, end of the day your product is not awful, but it's not necessarily the best I heard either.

5) The AP will not tell me exactly how something sounds. For that I would have to listen to that particular something and there is no replacement for that. But after a while, measurements do give me an idea of how something might sound based on previous correlation between sound and measurements. It's harder with good equipment, not so hard with wildly crappy stuff. In general, I would agree that transducers are easier to figure out than DAPs. But to give you an example, I can tell you it has become easier for me to figure out capacitor coupled DAPs that roll of in the bass area.

6) You are assuming too much. I have also listened to a few single-ended triode designs that I liked such as the Zana Deux SE. It actually measured fairly well given it's topology. The one I heard measured 10 ohms output impedance. But the latest iteration has a Lo-Z of 3 ohms. But yeah, in general those will not measure as well as other topologies when using the classic distortion test sweeps (which IMO are also flawed).

Regarding feedback awesome sauce: "I've never heard incredible sound from a solid-state design with high amounts of feedback."

So no feedback: http://www.innerfidelity.com/content/listening-stax-sr-900-and-great-hea...

Now w some feedback: http://www.innerfidelity.com/content/listening-stax-sr-900-and-great-hea...

Perhaps not exactly the same, but some feedback IMO can make awesome, awesomer. That said, I don't think feedback solves all the audio problems in the world.

Feedback measurements: "I know of no measurement that will definitively tell me if a solid-state design uses feedback or not, nor how much it uses"

Apparently these guys can:
http://www.innerfidelity.com/comment/496791#comment-496791

As far as measurements and real world experience, nobody is saying that folks need measurements to enjoy wine, beef, coffee, and one's wife kiss... But if you are going to drive, does it matter if you had half a pint of 3% abv beer vs. a six pack of 7% abv goodness? If you want to loose weight, does it matter if you ate one 95% lean 1/4 pounder vs. five patties of 50% loveliness? If you have acid reflux, does it matter you drank 1/2 a cup of regular coffee vs. 10 well measured cups of black coffee? If you remember the say 70% jasmine and 30% cinnamon perfume your wife wore the first time you meet, does it matter if you cheaped out and got her one with 7% jasmine, 3% cinnamon, 90% oxi-clean?

Charles Hansen's picture

Hi Castle,

Absolutely the last post from me on this thread.

Your point #1 demonstrates precisely why I don't like to have technical discussions about audio equipment. Please don't take this the wrong way. (It will be easy to do, as on the surface it sounds extremely condescending and insulting.) Please accept my apologies in advance.

You have just enough knowledge to be dangerous. You actually have shown me that you truly don't understand the issues involved here sufficiently to make any use of them whatsoever.

Your argument about maximum output power into a specific load impedance that varies with frequency is completely and totally irrelevant to any real-world listening experience.

Unless you were planning to listen to 20 Hz - 20 kHz sine wave frequency sweeps at maximum output volume so as to clip the amplifiers, there is absolutely zero correlation between the maximum output level and the frequency response interactions created by a non-zero source impedance.

As you are starting from a faulty premise, your conclusions are completely faulty.

Additionally, even if they were correct it still has absolutely zero to do with the listening experience.

I think the best way to leave it is to say that in my humble opinion, the PonoPlayer is not for you. I would strongly urge you not to buy one, nor even try one.

As noted in another post to another person, no product can be all things to all people. The PonoPlayer is what it is, and it is clear to me that it will never, ever fulfill your expectations. All you will experience from it will be frustration and irritation. That is not why we built it, so it would be a bad idea for you to own one.

There are many other players on the market that will meet your expectations and desires much more closely than the PonoPlayer. I would urge you to examine those other choices and select the one that suits you best. The PonoPlayer is simply not the DAP for you.

Best wishes on your musical journey, and I truly hope that you find what you are seeking.

All the best,
Charles Hansen

ultrabike's picture

LOL! this is Ultrabike. There is nothing to apologize. What we would be missing in those power numbers are the sensitivity numbers. But that's not the point. The point is that your player and a player with lower Z will yield different frequency responses and indeed different sound.

Music are not just single tones. But there are ranges that define bass, mid-range and treble (in general). And your amp colors those depending on the headphone load. It is what it is.

RE-READ the section "Blind Testing with Multi-Balanced Armature Driver In-Ear Monitors (BAIEMs)" in Tyll's article. It says that indeed your Pono colors the music.

"Your argument about maximum output power into a specific load impedance that varies with frequency is completely and totally irrelevant to any real-world listening experience... there is absolutely zero correlation between the maximum output level and the frequency response interactions created by a non-zero source impedance."

You are kind of putting words in my mouth. I never said maximum output level and frequency response interactions created by a non-zero source impedance are correlated. I kind of said frequency response interactions WILL EXIST between a 3 ohm source impedance and a 10 to 40 ohms headphone load. This should be kind of obvious to you.

I'll give you credit in that you mentioned that the lower the impedance of the load, the lower the output impedance of the DAP... Welp, based on what Tyll measured from the SPL plots in the section pointed to you above, apparently not low enough...

castleofargh's picture

First, before I start being a jerk, thank you for your time. We don't seem to be of like mind on a great many subjects, but I still appreciate you spending time to answer me, in action if not in content ^_^.

knowing there is some discrete stuff inside the DAP is ok for us, knowing the voltage of the battery(as if that was of any use for how the music sounds) is also ok and available anywhere. Talking about your opinion on feedback loop is ok. All the stuff about highres vs low rate mp3 were ok for 2 years...
But the output limits of a small battery powered device into a few loads, to know when the DAP might be voltage or current limited, and decide what we shouldn't use it with? Or when the pono will need a portable amp? That isn't worth knowing and not relevant to sound? And it's ok because others also don't do it? Well I know. if I wanted to know how it sounds I would listen to it. I want to know what it drives and when it will clip/distort. the answer to all questions can't be "listen".

Sorry I can't help but feel the cold hand of double talk and marketing. Even if you sincerely believe what you're saying, you're still cherry picking what we “deserve” to know. And I as a consumer certainly prefer to be the judge of which knowledge is relevant to my own needs. Else it's no less than being manipulated.

You give Bose as an example, well it's a very good example of what I totally despise. No transparency and people have for many years been sold a brand name. What a role model for all audio quality lovers.

Anyway I can apparently only wait for guys like http://headphoniaks.com/blog/ to maybe measure one. They tend to give the specs that I ask for, how strange of them.

Charles Hansen's picture

I'm sorry that you feel that way. Anybody who knows me will tell you that I am absolutely sincere about this and not into "marketing" nor "double-speak".

I used the Bose comparison as I found it humorous, but as I should know by now, humor doesn't translate very well to the computer screen. Sorry about that.

My honest opinion is that:

a) You are best off to listen for yourself and see if you think a headphone amp helps. I think you will discover very quickly whether the extra amplifier helps or hurts the sound. If you are having trouble hearing any differences, then you've just saved a pile of money. (Just as with the PonoPlayer itself. If you listen to it and don't think it sounds better than your current player, you've just saved $400.)

b) If you are (for whatever reason) unable to compare for yourself, then my opinion is that you will be much further ahead by asking for the experiences of fellow listeners on this forum and others (such as Head-Fi) than to rely on measurements. YMMV and apparently does.

Peace,
Charles Hansen

Charles Hansen's picture

Dear Castle,

I should really apologize. We are all just human beings and all doing the best we can and all are imperfect. I'm just an analog hardware engineer and tend to be very literal. My people skills and writing skills are not as well developed as my circuit design skills. (That's why Tyll is running this website and not I.)

Often things I write can sound condescending, although that is assuredly not my intention. When I re-read an earlier post I realized that it would be easily interpreted as "Hansen thinks he knows more than us because he had an experience at an early age, yadda, yadda, yadda.."

I'll give one (not too publicly embarrassing) example of how we can all fall short of our own stated goals. I've been hammering the point that one should simply listen to a piece of audio equipment to evaluate it.

When I was married (twenty years after I had that listening epiphany), my brother gave us the gift of a VCR. He had limited funds and therefore purchased an entry level unit from Costco. Being the equipment snob that I am, I was sure that I wanted a much higher performing unit than that.

I was lamenting the fact that there were no comparison reviews available to tell me which VCR was the one to trade the gift in towards (pre-internet days). A good friend (Hi! PHB) said, "Why don't you just compare them yourself at Costco?"

I felt pretty silly...

It had never occurred to me that I could apply the same experiences I had gained in audio to the video world. I was looking for external validation of my purchasing decision.

We hopped in the car and drove to Costco with the unopened wedding gift. At the store they had three or four different brands and models of VCRs. We looked at the same film on all of them using the same monitor. Sure enough, the one I had been given created a relatively poor picture. Two of the others weren't much better. But one model (not the most expensive, but I think perhaps second-most) created an obviously superior picture than any of the others.

I took that unit to the cashier, received credit for the gift player, paid the difference and went home very happy. That VCR gave hundreds and hundreds of hours of viewing pleasure. The combination of its performance along with the (at the time) high quality CRT display created a beautiful and involving experience for watching films. I never for a moment regretted paying the extra money for the higher performance VCR.

The irony here is that I had completely lost sight of my own direct experiences with audio and somehow convinced myself that they wouldn't apply to video. I didn't think that I would be able to tell the difference and sincerely wanted an "expert" to make my purchasing decision for me. :-)

If not for my friend gently reminding me, I would have been completely stuck. The truth is if that I hadn't been able to see any difference in the picture quality of the various VCRs, then I would have been just as well off with the original low-cost unit and saved myself a lot of money. But when I did take the time to look at it, I could see the differences and it was worth the money to me to pay for them.

The point is simply that we are all in the same boat. We are all here on Earth for too short of a time, and we are all trying to learn in the best way that we know how. Nobody gets out of this place alive, and we all need to choose how to spend our time while we are here and do the things that are important to us -- for whatever reasons that we have.

I've chosen to make the best possible sounding music playback systems that I can, as I truly believe that all people will have a richer and fuller life when they can deeply connect with the recording artist on an emotional level. Along the way I need to make enough money to support my family and ideally to have a semi-comfortable retirement. But I also know that this is not the route to fame and fortune. I don't know of any multi-millionaire audio equipment designers. (Actually that's not completely true, as they did not make millions of dollars designing audio equipment -- instead they received inheritances or married into money.)

When I participate on these forums, I'm honestly trying to share the benefits of my experience so that others won't have to bang their heads against the wall as I did.

Again, my sincere apologies if I sounded condescending, or like a marketer, or trying to manipulate you (or anyone else) as that is most definitely not my intention. Happy listening and enjoy your journey.

Charles Hansen

Guitarist9273's picture

I know they haven't been reviewed yet, but have you measured the Aurisonics Rockets, yet? You've mentioned them a few times and I'm excited to see how they measure up on paper.

I am grateful that there are reviews who do such an outstanding job of balancing subjective and objective approaches. I look forward to all of your reviews and content, but this was particularly good. Thank you!

Stefraki's picture

I've been extremely happy with the sound of my Pono; smooth, natural and comfortable listening. Considering the low price compared to other hifi portables, it's really very impressive and works joyfully well with my IE800.

I do find some of the practicalities a bit off-putting - slow start up, a UI without a lock screen making it easy to pause or forward a track when putting the unit back in your pocket, the unweildly toblerone form factor, and the thing gets HOT after a long session.

Its best functionality is sitting on a desktop, where the triangular form factor makes perfect sense, and it's now taken up the role of my office rig.

Currawong's picture

And it was fantastic meeting you at Canjam.

vbvb's picture

I'm a long time follower of your reviews. I like you detailed explanation and interpretation of the charts.

On reading this review I m reminded of my favourite sounding player, hifiman 601le. How would you compare Pono's sound with 60x's.

Thanks.

Stillhart's picture

Thanks for such a thorough review Tyll. After reading it, I find that our discussion at TGIFridays definitely became more clear.

I really like how you went to great lengths to try to separate yourself from the hype, both objectively and subjectively.

Regarding some of Charlie's comments about the player "getting out of the way", I wonder how the Pono would sound with the new Mr Speakers Ether. I found that to be a stupendously transparent headphone. Combine that with a transparent source chain and does it get you that much closer to the soul of the music? Or does it not work that way?

On a final note, I do hope they improve the user experience in a future model. I think it unfairly detracts from a great sound. Having the player get out of the way also means making it easy to get to the music you want.

Alex Halberstadt's picture

As others have written, congrats on a superb piece of writing, Tyll. I want to amplify one point that you made. After several decades of listening, I'm realizing that sound quality and the ability to emotionally connect with music sometimes have little in common. The former is fairly easy to quantify and seek out; the latter can be more difficult to identify. I got into the headphone hobby four or five years ago, and having now cycled through a number of expensive headphones and amps (HD800, ATH-W3000ANV, etc.) looking for better sound, I've found no more connection to the music than when I began. The other day, I decided to think back and identify every instance of getting lost in the music while wearing a headphone. To my surprise, every one happened while listening to the Sennheiser HD650 powered by a Crack Bottlehead or an ALO Continental portable (tube amps both). Go figure. I've since owned (and usually sold) equipment that cost more and sounded better, but there you go. Now, when I get lost in the music, I will try to pay more attention.

Charles Hansen's picture

Hi Alex,

Thanks for this. This is an extremely important point and one that is all too easy to lose sight of.

I would suggest that it's really not that hard to tell when one piece of equipment is more emotionally engaging than another. Following is what I have found to work well:

1) Select some music that you love because of the way it engages you and makes you feel.

2) Listen to several songs on that system and deliberately not try to analyze the sound quality. Instead simply listen to the song for the reason that you love it. Relax and enjoy it.

3) After you have listened to several songs, sit for a moment and recall your experience. Were you fully drawn into the music and forgot about everything else in the world? Or were you thinking about other things the whole time -- bills to pay, appointments to make, picking up things on the way home, an argument with your significant other -- anything besides being lost in the music?

4) Repeat those same songs and same test with a different piece of equipment and follow the same steps.

One or the other will be more compelling. Sometimes we will try to second-guess ourselves and say, "Of course I wasn't as engaged the second time around as I had just heard the same song a few minutes earlier. Naturally I would tend to be bored hearing it two times in a row."

This is assuredly not the case. You can easily demonstrate this by playing the first system again. Now you are hearing a song for the third time. If our idea were correct, we would be even more bored than the second time. But that is not what happens. If a product engages us the first time, it will also engage us the third time.

The only hard thing is to relax and let go and not try too hard. As Yoda said, "Do not try. Just do." Simply relax and enjoy the music for the reason that you enjoy it -- it makes you feel something. It could by joy or sorrow or regret or wonder -- it doesn't matter. That is the reason that we listen to music and also the reason that humans invented it.

Music is an essential part of the human experience. Some (eg, Daniel Levitin) argue that music is what makes us human, and that without (real, not MP3) music we actually lose our humanity. I tend to agree. YMMV.

Best,
Charles Hansen

Alex Halberstadt's picture

Thank you Charles for this lovely post. It amazes me that so few people in our hobby discuss the ability of a piece of equipment to engage the listener emotionally, as though it were something secondary, or something ineffable, and instead spend thousands of words dissecting dynamic range, etc. This may be the reason why so many of us end up on the wheel of buying and selling, mostly unsatisfied. And I do wish that more designers, like you, would include emotional connection as a design criterion. Otherwise, the product becomes just another gadget cluttering our lives. Than you again, Alex.

ulogin's picture

"3) After you have listened to several songs, sit for a moment and recall your experience. Were you fully drawn into the music and forgot about everything else in the world? Or were you thinking about other things the whole time -- bills to pay, appointments to make, picking up things on the way home, an argument with your significant other -- anything besides being lost in the music?

4) Repeat those same songs and same test with a different piece of equipment and follow the same steps."

This.

I am going to faithfully do the four steps today, and report back what I feel, sir!

I actually have three requests. I have been asking for these three things since the beginning of the Kickstarter campaign, but all I got was lip-service promises that "we will look at them":

1. Fine control of volume: Right now it's a 36-step volume control. It's not giving me the fine control I want when I use sensitive IEMs.

2. EQ: Which seems to be essential now given the output impedance.

3. Crossfeed: Which I deem is important for headphone listening. People who don't like it can just turn it off.

I guess these are all on the software side and thus are firmware upgradeable, yes?

Charles Hansen's picture

Thanks for trying the "engagement test". Let us all know your results.

Regarding the feature requests, I'm really not part of that loop. I can make a few comments:

1) Adding more steps to the volume control should be fairly easy. The DAC chip has many more available. I was kind of surprised that there were so few but have never had a problem with the headphones I use. I can imagine that it would be different with sensitive IEMs as the steps are larger at lower volume levels. I will check into this for you.

2) EQ has two problems. First of all I am philosophically completely opposed to it. Pono's promise is to deliver the original master tape (file) to the listener, just as the artist heard it in the studio. Messing with the data is simply not part of the equation. I've personally had this philosophy for the last 40 years and have never owned, designed, or manufactured a piece of equipment with tone controls.

Also (as noted in my manufacturer's comment), I strongly believe that Tyll is overstating the effect of impedance interactions. The "3.27 ohm" figure Tyll measured is not actually "the" output impedance of the PonoPlayer. In the first place it would be very difficult to measure this to ±0.3% accuracy as his numbers imply. The contact and wiring resistance of his test equipment would likely introduce errors greater than that. 10 milli-ohms is an extremely small resistance...

Secondly, as noted in the reply, a zero-feedback circuit will not have an artificially fixed output impedance like a feedback circuit does. Instead it will vary somewhat with loading and drive level, but in a good way that counteracts the interaction with low impedance loads. "3.27 ohms" only applies to one specific load impedance at one specific drive level.

I've not measured it myself, but would guess that the output impedance is more like 2 ohms when driving 10 or 15 ohm loads and will go as high as 4 or 5 ohms when driving 300 ohm loads. As noted before, this is a (good) self-compensating action that only can occur when no feedback is used.

Additionnally, the worst-case variations are only 1 or 2 dB. You will have massively greater variations from the transducer's inherent response, not to mention variations in how the 'phones fit each listeners ear/head. This can even vary from listening session to listening session.

The final nail in the coffin is that adding EQ would require DSP hardware that does not exist in the PonoPlayer. There is no room for it and it would decrease battery life.

Please read my other responses. It is impossible to be all things to all people. Or "performance, features, price - choose two".

3) Crossfeed is not something I've any direct experience with. I've spoken with some people who love it, others who hated it, and still others that initially liked it and then gave up on it. (I don't think I've ever encountered the opposite where someone didn't like it at first and then switched over and began to use it.)

Again it would either have to be done with DSP or by adding analog circuitry. Same as #2 above. Hope this helps.

Charles Hansen

cdanuloff's picture

It's very rare when the comment thread is better than the article, especially with such a fantastic post to begin with. I wanted to say thanks to Tyll for the awesome post and his ongoing contributions, and to Charles Hansen for jumping in here and sharing so much knowledge.

I'm a long time audio fan and not in the audiophile league of most here, but got a Kickstarter Pono and have been digging in and learning a lot (mostly to figure out which headphones to buy). This certainly isn't a market where there's a simple to find/follow Headphones 101 - and even after some serious work I can barely follow a lot of the math and electronics in this thread. But I'm getting there. I've bought a few pairs of headphones so far, and will continue trying learn more.

I really appreciate Mr. Hansen's articulation of not only the science but the points about numbers not being directly relevant or indicative of real world performance. For me you made your case very clearly and convincingly, and like Tyll's story about the experience of live music and how it relates to judging and experiencing the Pono Player, I think it provides an important perspective for all of us.

I can completely accept that there are numbers and they don't matter. That's not anti-science, it's embracing that there's more complexity than we can measure yet. And if people spending this much energy on listening fidelity don't know that music is complex and perhaps a little magical :-) they may have missed a step along the way.

Anyway, my point was to thank Tyll and Charles for their helpfulness to a beginner who does want to understand and more importantly make the right choices to maximize enjoyment.

- Craig

PS: My twitter review of the Pono was "Everything is wrong about this thing except the sound." and I stand by that. Horrific UX, form factor is cute but inconvenient, desktop software is terrible and the load process pathetic (USB3 please...). Hell they even picked the worst forum software for their website. But to me my Pono sounds fantastic - if they could only get one thing right I'm glad they picked that one. Kudos to Mr Hanson for this role in that too.

Charles Hansen's picture

Hi Craig,

Thanks very much for your comments -- it's nice to be appreciated! :-) I will attempt to address a few points in your PS.

1) I don't know how much of the UI factors into the overall UX, so will focus on just the UI. I would agree that the UI isn't sublime. A lot of that is due to the relatively small screen size. Most of the reasons for the small screen size were deliberate, such as fitting the form factor chosen and keeping battery drain to a minimum. Another factor is that the gestation period of the PonoPlayer was far longer than it would be from an Apple product. Without billions of dollars to throw at it, it took nearly three years from design to production. During that time the price of larger touchscreens fell dramatically. It is really just an reflection of starting a company from scratch that is attempting a gargantuan task.

As Neil himself has said many times, Pono is not like Minerva, perfectly formed and sprung from the forehead of Zeus. Instead it is a process and an adventure that will continue to grow and evolve over time. We have to be patient and do what we can to help.

There is no other company in the world that is trying make the complete ecosystem of players, desktop software, and a music store plus adding the formation of a community on top of that. Everybody else is just building IEMs or players and that's it.

Even Microsoft (at their peak, no less!) tried with the Zune and failed dismally. It's unrealistic to expect a start-up company to deliver everything with the velocity of the largest corporation in the history of the planet...

2) For every person who wants a thinner, more pocket-friendly case, there is someone else who loves the fact that it can be placed on one's desktop and operated with one hand. Everything is a trade-off and no product can be all things to all people. Overall I am very happy with the design. The only place it clearly will not fit is the rear pocket.

3) The loading process is slow, no doubts. Everybody blames this on not having USB 3, but that is not the bottleneck. USB 2 will do 480 Mbits/sec and if we convert to MB (as displayed on your computer's pop-up screen and take away 15% for control "overhead", that translates to ~50 MB/sec.

I typically only see 1/10 of that, so USB 2 is clearly not the problem.

Instead it is either the speed grade of the micro-SD cards (they include the lowest cost, slower ones for obvious reasons) or else some internal limitation of the main µP. I've not tried faster SD cards, so I don't know if this helps. I just queue up a dozen albums and then check my e-mail, so it hasn't been a problem for me.

4) The desktop software (PonoMusic World, or PMW) isn't as elegant as anybody wants, but it works well, is free, and is truly cross-platform. I don't believe that there is such a thing as iTunes for Linux, for example.

Please remember point one -- nothing in the world of Pono is "done" and never will be. Look at the player itself. Already there have been two signifcant improvements -- fixing the proper playback of gapless files and the addition of DSD playback. Both were free... :-)

5 I also have issues with the PonoForum and also blamed the software platform. It turns out that the exact opposite is the case. The software is capable of huge things that no other forum software can provide. All that is required are the resources to implement the changes.

It turns out that one of the incredible benefits of the software platform is that they can be implemented by developers from Pono. These are not fundamental limitations that would require the complete re-writing of the platform (which could only be done by the company that supplied the platform, in this case SalesForce).

Back to point #1. As the Pono organization grows more mature and gains a larger market share, the changes to the forum software will be made. Just be patient and you will see all of the things that you want. They just take time, that's all.

6) I'm glad that you love the sound of your PonoPlayer. In the end that is the ultimate gift, and it is here now. I loved the image that Tyll painted, hands hovering over the keyboard and unable to type as the music was so mesmerizing.

Mahalo.

cdanuloff's picture

Charles (if I may). Didn't mean to engage you on those issues... you've contributed enough. And I appreciate your points and understand them. However - this is closer to my world of expertise :-)

1) The screen size is a minor or negligible issue for me. The quality of that component in terms of sensitivity to touch however is poor. It reacts to unintended clicks (in my experience and from what I've heard from others) way to often. Too cheap a part I assume, or bad code running it. The 'floating scroll bar' is a joke, and the result is there's just no efficient way to scroll/choose music. I wish the album-cover view had a 4-up size, and a better A-Z picker was added.

2) My issue is less with the triangle (which has advantages as you point out) than with the buttons that stick out and get accidentally pressed when in a bag (a lock switch maybe?) and other things like screen and power controls. Very minor and I see the marketing advantages of being different.

3) If you take your SD cards and put them in a USB3 adaptor stick you'll see that it's the software and the USB2 both contributing to the speed. In that way it flies. Thank god side loading is allowed.

4) PMW is 'fine' too, but clunky and 1998 look and feel. iTunes is 2005, so the bar is low or this is hard for some reason. But I'm at about 120 HD/Flac albums and it ain't fun or pleasant. That's bad software. As to the forums, we'll have to disagree - configuration or not that system is hell for users and I have contempt and worse for any software company that would subject their customers to that. It's stunningly self defeating to want to build a community and ask them to wear concrete shoes and bags over their heads and then ask them to enjoy themselves. This is a well funded startup, with KickStarter and VC, and I am intimately familiar with hundreds of similarly funded and launch software companies and can't think of an example that tanked two major software efforts so badly. People should be fired and competent hires made - fast. A great user-experience (with PMW) and vibrant active community (that salesforce dungeon) could 10x the company, which I want to see succeed. There is literally just no excuse for the way they're treating it month after month after month.

None of these are your issues - nothing here aimed or intended for you to defend or react to. As I said you did the fantastic job. But as a user these are areas they have to work on. It's V1 so fine that they didn't nail it, I love that Neil started this and software/hardware ain't his world. I wish only the best for them and do appreciate what they've accomplished. But it's a consumer hardware/software company and there are standards and examples of what can be done. It's also a device that ONLY a hardcore geek could deal with in it's current form. With $13M or whatever they raised it's a lot more than this in these timeframes. I give them some slack on the V1, but the firmware updates have been minor in 4 months. I'll buy a V2 as soon as they announce and am sure there are lots of people working hard to get there. All comments are aimed (to them) as constructive criticism.

Charles Hansen's picture

Hi,

I appreciate you taking the time to clarify your concerns as they are truly helpful.

Best,
Charles Hansen

PS - Loved your title! I worked for a NASA contractor once and we had it down to a single word -- "Yabut" (rhymes with "habit").

castleofargh's picture

argh

"2) EQ has two problems. First of all I am philosophically completely opposed to it. Pono's promise is to deliver the original master tape (file) to the listener, just as the artist heard it in the studio. Messing with the data is simply not part of the equation. I've personally had this philosophy for the last 40 years and have never owned, designed, or manufactured a piece of equipment with tone controls.

Also (as noted in my manufacturer's comment), I strongly believe that Tyll is overstating the effect of impedance interactions. The "3.27 ohm" figure Tyll measured is not actually "the" output impedance of the PonoPlayer. In the first place it would be very difficult to measure this to ±0.3% accuracy as his numbers imply. The contact and wiring resistance of his test equipment would likely introduce errors greater than that. 10 milli-ohms is an extremely small resistance...

Secondly, as noted in the reply, a zero-feedback circuit will not have an artificially fixed output impedance like a feedback circuit does. Instead it will vary somewhat with loading and drive level, but in a good way that counteracts the interaction with low impedance loads. "3.27 ohms" only applies to one specific load impedance at one specific drive level."

So your solution for the pono, a portable device made to use with portable stuff, is not to use 95/100 of the expensive IEMs and custom in ears on the market. As they will have a low impedance and a few crossovers.
or just accept that they won't have the FR designed by the IEM manufacturer. Because hey who cares about that guy right! I just gave him a thousand bucks to get his product, why would I care if the signature were to change by several db! That makes sense...
I agree that no headphone is flat, but we still pick them mostly based on FR.

you don't want EQ. I couldn't live without it. But I understand now that I get to know you a little. That's coherent with the rest of your "philosophy". If you truly believe that timing is all(and you do else you would use feedback to get stability), then phase shift and maybe pre ringing from an EQ won't make you happy at all however small those stuff might be. I get that.

Anyway, once again you're not even the ugly duckling as many DAPs have above 1 or 2ohm impedance. And at least you get high impedance for a reason. But once again, if you had provided some specs from the start(like an average impedance), many people would have been informed of the risks of sound change for some of their IEMs. So IMO you should be required to give such information. Or at least feel compelled to do it not to misguide people. That's been half my point from the start(the other half being personal curiosity ^_^).

davedcawley's picture

I'm not good with math like you guys are, but I've got ears sensitive enough that I could point to the TV in the TV store that was still on with no picture on it. The sound I get out of my Pono player is great, even listening to the same flac files on my laptop or desktop with my Shure SE215 IEMs doesn't touch what the Pono player does. I can hear the space between the instruments. I completely understand your frustration at finding yourself sitting there, fingers above the keyboard. I now drive slower to be able to listen longer and I will take the long way home or sit in the car until the song finishes which makes the dogs bark and drives my wife crazy (it's a double win).

Yes, the interface sucks, there's no documentation on how to operate it when you open the box, the triangle shape is cumbersome, the battery could last longer and the Pono Music World software is buggy and hangs a lot. But all that aside, I haven't heard music this clear in decades. Even when I've got it connected to the audio system in my VW Routan, it is still is a great listening experience. One surprising thing is that the Pono music store has some very obscure 80's alternative music that I can't find anywhere else other than buying the vinyl from someone on Ebay. They have also been really good at taking suggestions from the community for fixes to the software and firmware. Some of those suggestions have been implemented in both.

So, no, they haven't cured cancer, but they've created a really great listening experience and made me very happy. In the end, that's what it's all about.

burnspbesq's picture

I used the Pono Player as source and DAC when auditioning the prototype Cavalli Liquid Silicone portable amplifier at CanJam over the weekend. The combination sounded extraordinarily good to me with UERM, which is a highly problematic headphone when used with the Pono Player's single-ended headphone output.

ultrabike's picture

Yours is an honest opinion which I very much respect. Thanks Paul!

Whatever the techno-babble I'm reading, it's not a bad player. It may still interact with the UERMs since the impedance may tank a bit in the treble and mids region. But I can see it working out.

hackmartian's picture

First off, great review — this was the best, most balanced and thorough review of the Pono player I've read. It was refreshing to read an evaluation without prejudice!

As for my own experience with Pono, I excitedly bought one last week and my first reaction was similar to yours — I listened through my Rockets and was floored at the sound quality. I'd demoed an early prototype and was impressed then, but completely wowed by the final product's sound. I got completely lost in what I was hearing and thought I'd finally found the perfect portable. Then the reality of the rest of the Pono universe set in: The app interface is clunky, dated and buggy. It's absurdly slow to load music on to the machine, even taking the size of the files in to account, and far too complicated to take music off of it. The first-generation iPod was simpler and faster. Overall the software and store experience feel dated and fussy.

I was also frustrated to see the vast majority of the music on the Pono store is not hi-res, but standard CD quality (and they were missing many albums that are available in hi-res on HDTracks). Now that Tidal exists, why purchase a CD-quality download that costs half of an unlimited monthly subscription? Since the Pono has no wireless connectivity, that's not an option. [Side complaint, why do hi-res music files in general cost more than physical goods and other downloads anyway? It makes no sense that the physical CD is more expensive than a download of the same file given the lack of manufacturing, warehousing and packaging — I realize this is less Pono's fault than the labels who set the costs, but it affects the practicality of a dedicated download player that can't stream].

All of these frustrations culminated in me returning the Pono just a few days after buying it, which is a shame. They nailed the sound but everything else is a decade behind the times. Which is a shame. Because, damn, did they nail the sound.

Bumpy's picture

This review beautifully captures my experience with Pono, and all I've done is side load directly onto an sd card then put the card in my pono. I haven't even downloaded the desktop software, too easy to go straight to the card (and super fast).

For me the open ecosystem is as important as the great sound. I can wait on v2.0 software. I'll also let more discerning listeners help fund the hi-rez catalog and startup costs for the music store. When value improves I'll buy from pono.

In the mean time I'm loving the sound and couldn't imagine returning a pono over gripes about slow loading and overpriced content that are easily worked around.

Now if I can just decide on the right headphone upgrade. Spending way too much time reading Tyll's many terrific reviews, for which I am very grateful!

hackmartian's picture

Honestly, Bumpy (my high-school nickname, actually!), I didn't attempt or even think to try just loading directly on to the SD card. Seems like a reasonable solution and I might have held on to my Pono if I'd found that faster and easier. Still, in my heart, I'm a plug-and-play audiophile. I get that there's always a battle between quality and convenience but so much of what Pono got wrong in terms of the UI of their desktop and store software are problems that have been solved for years.
After returning the Pono, I decided to divert that money to an Oppo HA2 DAC/Amp, which has turned out to be a nice little solution so far. Using the (admittedly also clunky) Onkyo iOS app, I can use my iPhone to store and play hi-res audio files in to the Oppo, which is phone-sized and well built. I can also run stream Tidal from the phone into the Oppo, so no need to bother clogging my hard-drive up with ripped CDs. It ain't perfect, but it's a little closer to the goal for me.

Bumpy's picture

Glad you found a solution that works for you. I definitely get the frustration with poor usability. Although there is no perfect player, we are blessed to have so many good options - worlds away from taping cassette tapes back together! These are good times for music lovers.

hackmartian's picture

I listened to the Pono with both Aurisonics rockets and Audeze LCD-2s, both sounded terrific.

hackmartian's picture

Sorry--in the above rant on the cost of downloads, I mean to say "it makes no sense that a physical CD is CHEAPER than a download of the same file..." and not "more expensive.'

VeggiePopper's picture

Have you tried the Pono Player with the Sennheiser Momentum?

IIRC the Momentum were at some point part of the WoF, but knocked off by the NAD VISO HP50, which you did mention in this review. Since the two sets of cans share many similarities, would you think the Momentums to be compatible/recommended for the Pono Player?

Paul Engel's picture

I loved the review, I loved this thread (particularly the contribution of Charles Hansen), but that's not the best part. The best part was getting my Pono as a gift and finding Simon and Garfunkel's "Bookends" in the highest sample rate possible. I don't have any of the fancy headphones mentioned in the review, I just used my Bose QuietComfort's. And I put them on and ...

...

...

somewhere before side one was finished I noticed my eyes were flush with tears. What the hell? That's never happened to me before. Was it nostalgia being that I've listened to this album since I was 8? I've heard it hundreds of times in the past but not like this. Never like this. I'd prefer not to over-analyze it and to just own and enjoy the experience.

I heard everything. and new things. I especially loved hearing Wrecking Crew's Joe Osborne's bass playing. Simon's guitar picking. the vocals ... everything just came alive.

Thanks to the Pono team for all the effort you put into this product. Thanks for the great review which pushed me over the edge to get it.

Now maybe I need to look into some better cans for it ...

JoeJoe133's picture

This is what I sent to Pono support about my 1 month old Pono player after 1, 3hr. use, and their response:
Hello,
I purchased a yellow Pono Player from Frye Electronics on 5/11/2015.
I used it about 2 weeks ago on a flight from Indiana to Florida & back.
That is pretty much the only time that I have used it over a few minutes at a time.
I am very happy with the sound, but have noticed that dark marks have started appearing on the yellow surface of the player. The black areas on player are mostly on the corners of the player. It looks like its been burnt from the inside or something.
I saw on the website that at least a couple of others that I can find have the same issue.
The only thing that I can think of that would cause the dark spots would be from overheating, or maybe from the airport X-rays?
I have tried to clean it because I thought it had somehow got dirty, but it appears to be inside or under the yellow finish.
For the amount of money that I paid for the Pono I would not expect it to look so bad with so little use.
Please advise.
Thank you.

Supports answer;
"Thank you for contacting Pono Support,

Unfortunately due to normal wear and tear this is common on the yellow Pono.

The dark spots can appear from having it in your pocket, in a bag, carrying it in your hands.

Any friction can cause the discoloring of the edges.

The discoloring or dark spots are not caused by overheating.

The discoloring is not covered under the warranty since this is just normal wear for the Pono.

Mahalo,
RyanEdit"

Notice that they said that it is "Common on the yellow Pono"
Sounds like their quality control standards must be very low, to non existent.
I wonder if Neil Young is aware of the "common" problem with their materials used?

Bob San Diego's picture

Thanks for your review of Pono as well as your explanation of how to evaluate which headphones should work best with this device. I am ready to step up from my Koss Porta Pros (which I love) to the next level for listening to music on my Pono Player. I am looking for balanced headphones to take advantage of the balanced output of the Pono Player. You make a compelling argument for the "tried and true" Sennheiser HD600s (300 Ohm) which should be sufficiently driven by the amplifiers on the Pono. However, you and many others also love the sound from the Hifiman HE400S planar magnetic headphones. Will the low impedance HE400S headphones (22 Ohms) exhibit tonal distortions that you described for the low impedance IEMs in your article when driven by the Pono with its 3.27 Ohm output impedance?

Don Ho's picture
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