A Trusted Traveling Companion: The CEntrance HiFi M8 Portable Headphone Amp/DAC Measurements

Measurements
Click on graphs image to download .pdf for closer inspection.

I'm still working on refining my headphone amp measurement automation routines, and for the HiFi-M8 I had to modify the existing routines for ditital input instead of analog input. So, there's a step forward, but in the process I also saw some things I'd like to change. At any rate, it's still early in the process of amp measurements, and I've got a lot to learn about what to expect when viewing these measurement, so I'll only point out a few things I noticed and leave any further interpretation to the reader.

CEntrance HiFi-M8 measurements were primarily done with a 0dBF digital Toslink input signal and most measurements taken with output set to -10dBU. All measurements were done under battery power.

Frequency response is flat between 100Hz and 20kHz. This amp is DC coupled throughout, so the roll-off below 100Hz is likely due to a DC servo circuit used to null and DC offset. As very low frequencies begin to approach DC they begin to be effected by DC offset servo circuits. Low frequency response in listening was excellent; I think the reader should not be concerned with this roll-off.

THD+Noise vs. Output Vrms shows an amp with reasonably low distortion, but having very high output power and voltage capabilities.

Noise spectrum shows a noise floor at about -125dB. A small artifact at 15kHz can be seen. My guess is we're seeing some crosstalk from digital circuits. With a peak at -100dB this will have very litte effect in listening.

500Hz Harmonic spectrum shows very little harmonic content. The second harmonic at 1kHz is 80dB below the fundamental, the third harmonic at 1500Hz is barely above the noise floor, no other harmonics are observed. Harmonic distortion is therefor dominated by the even order second harmonic and likely would contribute some euphony to the sound. In listening I was always struck by the lack of "solid-state hardness" of this amp.

Both SMPTE and CCIF IMD plots show very little in the way of intermodulation distortion artifacts.

Crosstalk is very low.

Single point output impedance reads 1.58 Ohms in the 1 Ohm switch setting. It's very likely the additional half Ohm is due to cables and connections. At some point I'll independently measure the cable and connection impedance of my set-up and subtract it from the measured value.

These are very good measurements for a portable headphone amp in my limited experience.

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CEntrance, Inc.
8817 Mango Ave
Morton Grove, IL 60053
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COMMENTS
johnjen's picture

It's good to see measurements for electronics appearing. :thumb

A long awaited 1st for headphone gear. :thumb

 

JJ

gjcsima's picture

Would be interested to find out where some of the top in-ear phones compare to some of the top over ear phones?  Maybe have a shoot out of overall sound quality for all types of phones and then value...

lithium's picture

I am personally not a big fan of carrying huge rigs outside home. So how is its performance relative to a home use unit (in the same price range) say something like the ALO Panam or the modi+magni? Like you mentioned before note in power but in nuance and ability in the small stuff

vickibee's picture

I'd happen to agree with you, I find it hard to carry around an amp, in addition to some bulky headphones.. I currently use the Sennheiser HD 600's (a headphone amp really is needed though). I've been using the Magni 2 amp I found here http://www.pricenfees.com/best-portable-headphone-amp.html . It is pretty small, doesnt usually overheat like some other amps I've been lucky enough to try (even getting burned, lol). Although it probably can't compete with the CEntrance HiFi M8 - it does the trick when I'm out and about!

Long time listener's picture

After reading about the implementation of tone controls here, I've changed my mind and decided this isn't something I want to buy. Shelving filters of the kind Tyll mentioned he would like to see have long been successfully used in integrated amplifiers and elsewhere. They usually slope gradually up until about 100 Hz in the bass, or 10 Khz in the treble, and then begin to level off. They work great and sound wonderful. (For a classic example see the Sterophile measurements of the NAD M3 integrated amplifier: by 100 Hz and 10 Khz the slopes are nearing their plateau.) But lately people have this idea that they need to keep the bass and treble controls "out of the midrange," and those two points are moved respectively much lower and much higher. In my experience, the midrange was never seriously affected by traditional tone controls, and with this new type, all I get is some serious hiss in the high treble and some dull thudding at the very bottom of the bass range--but no real perceived change in bass or treble levels. It's only when you include at least part of the mid-bass and the mid-treble that the ear will hear much of a change in the bass or treble regions. Certainly the midrange is very important. But if the midrange runs from about 250 Hz to 2-3 Khz, any tone controls that slope down from 100 Hz and 10 Khz are already well away from the midrange; their gradual slopes may enter part of the midrange at their shallowest points, but that just provides a necessary transition. Get some sense, people, and stop ruining our audio experience with weird tone controls. The ones shown here don't look useful to me at all.

Dan S's picture

And why do these tone controls on the M8 only boost either the treble or bass? I would prefer the option to boost or cut. For headphones that are too bright, nudging down the treble is often preferable to jacking up the bass. I really like how the FiiO E17 Alpen actually has tone controls like this. They're so hard to find on headphone amps!

Willakan's picture

As per the title, it is great to see the amplifier measurement program producing its first set of measurements in a review - your hard work on it is paying off! A couple of observations:

1) There seem to be some missing curves in the THD+N graph.

2) With a quick glance at the relevant masking curves, it seems extremely unlikely that the second harmonic, being about 80dB down, would contribute anything to the sound, IMHO. These thresholds were arrived at with test tones: I would expect things to be considerably harder to hear with real music.

3) I realise that I'm really looking a much awaited gift-horse in the mouth at this point, but to my mind some THD vs Frequency sweeps at the same output level you produce the 500Hz spectrum would make an extremely valuable addition to the datasheet. Most amplifiers do not offer frequency-invariant distortion performance, especially into low impedance loads.

Anyway, to reiterate, it's great to see an amp review with a measurement section :D

nnotis's picture

Thanks for comparing this to your reference desktop system.  It's good to know where portable gear stands relatively.  I wonder though, was it the M8's amp or DAC that served as the limiting factor?  What headphones did you use for this comparison?  With HD800s & LCD2s, I'd expect the amp to be a factor.  But what about with IEMs?  I've found portable amps to be completely up to the task of driving them.  It's the portable DACs that can't match the focus of my desktop one, thus becoming the weak link in my portable chain.

HeadphoneAddict's picture

Hey Tyll,

I enjoyed your review. I did want to mention that I received one of the first units, and it has worked with the lightning cable with my iPhone and iPad out of the gate. Also if you get the Apple USB camera connection kit, it can be plugged into the other USB port to do 24/96 with an iDevice.

Someone else asked whether the DAC or the amp is the weak link. I think the DAC is fantastic, and the amp is pretty darn close. I do prefer using an external amp with my Sennheiser HD800's, but the built-in amp is very acceptable with everything I've tried. The HD800s can be picky & seem to work better with a very warm sounding amplifier, and my HD 800s have not been modified like Tyll's. Less than half my desktop amps at home do justice to the HD800, and only two of them make them sound their best, but none of them sound terrible with them. I do like +3dB bass and 10ohm output impedance, with my balanced black dragon cable when I use the HiFi-M8 with the HD800.

Cheers,

Larry

PS: Nick, it's great with my JH16Pro, ES5, Westone 4, and Primo 8 IEM - all very different sounding IEM.  Primo 8 do better with 10 ohm output impedance and +3dB bass, and I like to add treble with the W4.  The customs need no EQ or impedance increases.

Alberto Martinez's picture

Looking at HiFi-M8 specs on Centrance website it says iDevice jack only supports 16-bit/48kHz and my music source is my iPad with FLAC files on 24/96 and 24/192? I have Apple CCK cable and normal ligthing. How do I get at least 24/96?

Looking at specs iFi micro iDSD seems higher device, what do (any of) you think? I will pair with Senn HD600 300ohm impedance.

I am looking for a portable DAC/Amp additional to my desktop Schiit Asgard 2 Amp, that I love the sound.

Thanks for your answers/comments.

HeadphoneAddict's picture

You can use the CCK with a USB adapter cable to connect the HiFi-M8's Computer USB port to the iDevice, and then use a FLAC player on the iDevice to play 24/96 through the Computer input - the iDevice input doesn't go over 16/48 yet.

AGB's picture

You can't make up your mind about how the M8's "tone controls" work unless you heard them yourself. You cannot imagine how they'll sound either. They happen to work well, but not as well as let's say Fidelia Advanced music player's parametric EQs will. But then you won't have to lug a computer around either. I use the EQs built into the iPod Classic in stead...but 95% of the time I use the M8 at home with my Mac anyway.

For home use I leave the EQ for USB on the M8 off at both lows and highs and use Fidelia's parametrics for whatever headset I am using - and yes, they ALL need EQ, every single one of them.

The impedance switch is what makes this man stand apart from the boys. The lowest with both headsets I am using makes a large audible difference. The low gain setting another audible difference, as it allows the volume pot to rotate at the settings where resolution/loss of bits will be least impacted.

Lastly Tyll, it's a great review and about time. The M8 may be the best of the the breed regardless of cost. I am curious however if you used the same source going to the M8 as you used for the Aurilic. Again, we are speaking about comparing  a $5000 Aurilic DAC and Amp vs $700 for the M8.

Perhaps a little tweaking of the EQ will level the playing field in such comparisons?

I think it'll make things close enough and that'll be telling about how good the M8 really is...it is really, as Tyll says, that good.

I wish it were smaller yet. I wish it would dispense cappuccino, I wish....

sgibson389's picture

What are the black bands holding your amp & player together? Thanks

Long time listener's picture

"You can't make up your mind about how the M8's "tone controls" work unless you heard them yourself. You cannot imagine how they'll sound either."

Well, if I've heard two pieces of equipment that use tone controls similar to the M8, and I didn't like the tone controls on either of them (and that is the case), I can in fact be quite certain I won't like them on the M8 either. That's the beauty of having measurements to let you know whether something is behaving in a similar way to another familiar piece of equipment or not.

Having said that, the bass on the M8 is different than what I described above. But I've found Tyll to be a very honest and trustable reviewer, and if he would have preferred shelving controls ...

ricks0me's picture

Tyll: I have to disagree with you on this one. No bass or treble tone shaping for me. Other than this, you are usually right on target. Best Regards / Rick

Tyll Hertsens's picture

...of the off position of the switches.

spyder1's picture

Tyll,

Where did you obtain your short Toslink patch cable, for this Astell&Kern AK120, CEntrance HiFi M8 combo.I have a AK120, and would like to mirror your set up.

Paul Novitt

AGB's picture

Mikel Mercer informed me that the balanced out does not respond to the impedance switch - perhaps understandable as it may be already at a very low impedance...one reason why it sounds so good using balanced Moon Silver Dragons.

I do have reservations about making comparisons with a separate DAC-headphone amp, as it is impossible to separate the DAC from its hadphone amp in the M8. As stated earlier, i believe a judicious adjustment with a parametric EQ will make most, if not all, differences one might hear in such comparisons vanish.

Another reservation apart from testing methadology is battery life, with some competing units providing substantially longer play time.

The plus end is that the M8 is strikingly good sounding with CD's, to the point one may not care that much about going higher rez...even of one can hear a bit more naturalness with hi rez on some, not all, material. I compared CDs with HD Tracks downloads on both the M8 and a $2500 DAC of high repute and the M8 wiped the floor with it with CDs. I just wanted a portable DAC, not a home model. So....

To my chagrin, as I had to resell the other DAC, as much as I liked it.

AndrewG's picture

Your comments are great. Very helpful in giving some additional context. Thank you!

mgoodman's picture

Michael Goodman from CEntrance here. Wanted to say thanks to everyone who contributed. We enjoy the discussion.

Regarding EQ, I understand and agree that HiFi-M8 (pronounced "mate") does not follow the 70's tradition of a "smiley face" EQ found on most consumer amps. That's on purpose. I've spent years in recording studios, working with anything, from classical, to rock, to jazz and can tell you with confidence that certain frequencies are less desirable to the ear than others. One such area is "midbase", which is frequently referred to as "mud" by experienced recording engineers. It's too easy to make the sound lose calrity if you boost that region, so we decided to "not go there" with the EQ on the M8. Instead, we chose to boost a very specific area of the lower bass range, which plays well with modern music styles and favors electric bass instruments (stringed and synthesized). Many of our listeners are of the younger generation and therefore experience more synth bass than acoustic contrabass in the course of their day. I guess you can say that we caved in and made a slight nod towards popular music :) But turth told, classical sounds as great on the HiFi-M8 since all the fundamentals of good design are preserved.

Let us know if you have amy other questions, either here or by sending us email. We love to talk this stuff.

Tyll Hertsens's picture

Thanks for posting up, Michael.  (Sorry you had some trouble getting logged in.) I appreciate your philosophy...even if it differs from mine...and I definately appreciate your overall approach with the M8. You've really done a great job creating a product that is extremely versitile and well suited to a wide variety of users. Great stuff!

SBranson's picture

I bought this based on this review but it does not drive the new HiFiMan HE560s very well at all.
There's just not enough gain. I have this on max gain setting and the dial at 2 or 3 o'clock and with some quieter recordings I can turn it the volume all the way up and it's still just starting to get loud but not even too loud to listen. I hate the sound of setting an amp on high gain anyway but this is beyond that..
The HE560s are supposed to be easier to drive than the HE-6s and even the HE-500s.

These certainly don't "drive anything".

SBranson's picture

Just to qualify my earlier comment... Not all recordings are that bad. Some work fine but there are several that this will barely render loud enough.

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