The Revolutionary Astell&Kern AK240 Hi-Rez Portable Media Player

Astell&Kern AK240 ($2500)
When I was in high school I had a big glossy poster of a bright red Ferrari against a dead black background in my bedroom. I lusted after it...I hoped against hope one day I could afford one...I never would. Oh well, that's the way of the world: Some people will have things that you never will. Get used to it.

Such a thing is the Astell & Kern AK240—the Ferrari...hell, the Bugatti Veyron, of portable media players. The question is not whether the AK240 is worth $2500 for most people—it's not, most people simply shouldn't be spending this kind of money on a player. This is a luxury/enthusiast item. The question is, if you've got the passion and money for these types of killer gadgets, does the AK240 deliver passionately on that money spent? Is this a worthy super-toy? In short, yes. This is excess at it's finest.

There's a lot of ground to cover, so I'll dig right in...

AstellKern_AK240_Photo_Front

Physical Description
The AK240 boasts an aircraft-grade Duraluminum chassis that starts with a single 435 gram billet of the material. It then goes through a complex 12-step process of machining, finishing, anodizing, and laser engraving to complete the finished enclosure. A full description of the process can be found here. The result is a flawless deep champaign finish; a brilliantly durable exoskeleton; a drop-dead gorgeous piece of kit in hand.

Speaking of "in hand", my first thought on seeing this unit was "gorgeous"; my second thought was this thing might be uncomfortable to hold. I've not found this to be the case. In part, the leather case (pic next page) softens the angular shape, and in part the position of the volume control is much more ergonomic than it might appear, but I think in the end it never bothers me because my mind never really gets too far past that on-going initial impression, "My goodness, this thing is gorgeous."

A 3.31-inch AMOLED WVGA (480 x 800) touch-screen display is a tad smaller than most smartphone displays, but provides plenty of space for comfortable control in use, and at maximum brightness is easy to read in full sunlight.

AstellKern_AK240_Photo_Rear

The rear of the unit is spectacular with a carbon fiber panel under a deep gloss finish. The play of light on the warp and weft of the material give a distinct impression of depth. The metalized Astell&Kern logo on the rear panel seems to float 1/4" above the carbon fiber panel beneath...a luscious optical illusion.

AstellKern_AK240_Photo_Top

The top panel includes a 3.5mm headphone jack that alternatively functions as an analog line out and Toslink digital optical output; a 2.5mm TRRS (tip-ring-ring-sleeve) balanced headphone jack; and the power button. One note here: the DSD format is not supported when using the optical output, and the optical output is unavailable when the AK240 is used as a USB DAC.

If you've got headphones on and turn on the line-output function the output goes to full volume and cannot be adjusted by the volume control, so you might get your ears blasted if not careful. If you've got normal Toslink cables and want to use them with the AK240, you'll need one of these adapters.

AstellKern_AK240_Diagram_TRRSBalancedConnectorBalanced headphone drive is a special method for driving headphones that removes he common ground and reduces cross-talk found with normal headphone connections. For more info see this page. The AK240 is fairly new, and balanced 2.5mm connections are rare; I've not been able to find anyone with a hearty range of adapters for this balanced output yet, but no doubt ALO Audio, WyWires, and Moon Audio will be developing a range of solutions. Give either one a call and I reckon they'll have a solution quite soon.

The power button takes a "long push" to turn on and off; a short push while on will turn the display on and off. When off, holding the power button in for longer than 12 seconds will trigger a complete re-boot of the player. I did have one instance of it locking up—powering it down and then re-booting had back in operation quickly.

AstellKern_AK240_Photo_Left

Track control buttons on the left-hand side of the player are responsive and intuitive for audio enthusiasts with a standard push to track forward and hold to fast forward method. It's the details that count with a luxury product. The buttons are small with elegant < l> > glyphs; their actuation clicks nicely at the tip of your finger; and the function of the buttons while inside the leather case remains flawless.

A microSD card allows for 128GB memory expansion to the 265GB internal memory. Astell & Kern recommend SanDisc Transcend memory cards. Once inserted, the SD card will be mounted and scanned for music. Music on the card will appear on song, artist, genre, and album lists along with track in main memory; the folder view changes to display "SD card" and "Internal Storage" as the initial navigation step.

AstellKern_AK240_Photo_Bottom

The Micro B USB connector on the bottom panel allows you to charge the device; transfer files; and use the AK240 as a USB DAC. Transferring files and using the AK240 as a USB DAC is not entirely plug-n-play; depending on whether you're Mac or PC centric the procedures differ, for full information see the manual. I did try file transfers and use as a DAC with both Mac and PC machines; set-up was painless and operation smooth. Note: when used as a USB DAC EQ controls are disabled.

Also on the bottom panel are a couple of small Torx screws presumably for taking the unit apart—not going to do that, nope—and a laser engraved serial number.

AstellKern_AK240_Photo_Right

And lastly the right side where, it seems, all the post-modern angles of the AK240 collide to form a bastion of security around a humble, knurled rotary volume control. As unfamiliar as this configuration might look, it worked and felt completely natural in my hands...and more so when in its leather case. I found myself generally using the knob for fine adjustments and my finger on the display for larger ones. The drop-down notification bar does have a volume lock which allows you to select whether or not the volume control is active when when the display is off. I mowed the lawn a few times with the AK240 in my pants pocket without the volume locked and had no problems with inadvertent volume control changes.

Specs and Functionality
Where do I start? It would be easier to describe what the AK240 doesn't do. Let's start with the specifications list:

AstellKern_AK240_Photo_Fronthart_Specs

Of particular note are the Cirrus Logic CS4398 dual DACs and the unmentioned custom XMOS chip that allows the AK240 to play DSD files natively. As you can see the list of file formats supported is quite comprehensive.

Output impedance is stated as 1 Ohm. I manually measure the output impedance using a 500Hz .WAV track. Full volume open circuit voltage of this track was 1.07 Vrms. Placing a 32.5 Ohm resistor across the output to ground reduced the output voltage to 0.973Vrms. This calculates to 3.24 Ohms. Measured resistance of probes and connections was about 0.3 Ohms. Out of interest I measured the AK120 I have here and got essentially the same figure at 3.29 Ohms.

Music Sources - Obviously, the AK240 can play files stored on the 256GB of internal memory or the up to 128GB external microSD card. As mentioned previously, it can act as a USB DAC/headphone amp. And it can stream music from a host computer on your network, though it will not stream directly from an NAS drive.

To use the MQS (mastering quality sound—Astell&Kern's term for hi-rez files) streaming function you'll need to load the MQS Streaming Server software onto a Mac or PC in your home. I installed the app on a PC and mapped the Bluesound Vault drive as a virtual drive on that machine. Once the app was installed I selected the mapped drive as the source for music and it worked beautifully. Initial set-up will take a little while as the MQSSS software will spend some time indexing all the tracks.

Music Outputs - As mentioned above the player's headphone jack can drive a headphone, can act as a line-out (latest firmware has additional line-out select on the volume control screen), and a Toslink digital output.

The 2.5mm jack will drive balanced headphones. I'm a little leery of using a 2.5mm jack for balanced cans as they're somewhat fragile and the adapters that will be created to couple this jack to the various balanced connectors will likely be somewhat heavy. I suggest strongly that adapters made should have a long enough cable so you'll be able to handle the player with the adapter/headphone connectors remaining on the table. None the less I do undertand the need to make the balanced connection a different size than the standard 3.5mm jack so as not to confuse folks or allow the wrong type of connector to short out the contacts. C'est la vie.

The AK240 can also act as a Bluetooth v4.0 A2DP source. The previous Bluetooth implementation on the AK120 was very poor in my experience; the AK240 Bluetooth connection performed flawlessly. I know it might seem a little silly focussing in on the Bluetooth performance of a hi-rez player, but I think it's terrific to have when on the move and using a portable Bluetooth streaming speaker. The AK240 will not transmit DSD files over Bluetooth, and Astell&Kern recommends files of 48kHz sampling rate or lower for drop-out free playback.

Playlists - A huge improvement here over the AK120, the playlisting functionality of the AK240 is superb! Just press and hold your finger on any song, album, artist, folder, or genre; when the item shows ready to drag and the display changes to allow you to drop the item into a play list; the display switches and you select which playlist you want the item on. In other words two swipes of your finger and you've added what ever you want to a playlist.

Equalization
AstellKern_AK240_Photo_EQScreenThe 10-band graphic equalizer is also a solid improvement over the AK120s 5-band. The EQ has an interesting UI: you can either just draw an EQ with your fingertip across the screen, or you can adjust the sliders one at a time. I found both modes a bit hit and miss. The drawing mode seemed to not quite accurately enough follow my finger tip—not sure whether it was my drawing skills or inaccuracy of the UI, but I always had to go back and adjust it slider by slider after my first course pass with my fingertip. And the slider by slider mode was made difficult by the accuracy with which you need to touch each slider—if you miss, the AK240 thinks you're drawing a line and the sliders move around somewhat erratically. Though it was a bit difficult I did always manage to get what I wanted in the end; EQ profiles can be stored and easily switched between after being saved.

One thing to note: when the EQ is turned off on the drop-down menu it significantly changes level which can shift the perceived EQ a bit. I thought it might be reverting to the ProEQ setting, but that doesn't seem to be the case.

AstellKern_AK240_Graph_EQsettings

The graph above was taken using a white noise track I have in my test tracks and my AP2522 acquiring FFT FR data. The overall upward slope of the curves may simply be a miss-calibration between the noise and my FFT settings and I think should be ignored as an absolute measure. Because this is a measurements of a noise signal it was averaged over 64 measurements and then significantly smoothed to reduce the noisy nature of the data and so that the larger EQ differences are readily apparent. It should be a reliable indicator of FR differences between EQ settings. As you can see switching between a FLAT setting and turning the EQ off gives a pretty healthy (~3dB) increase in gain, but does not show any significant changes in EQ. The Pro EQ setting does have a broad increase of about 1.5dB in the mid-range, and possibly (because this could be just a noise artifact, but I doubt it) a slight lift in the top octave. Generally speaking, I preferred the unit set to flat or drawing a custom EQ rather than use the Pro EQ setting.

Over-the-Air (OTA) Updating
The beauty of a highly programmable device like the AK240 is the ability to upgrade and add functionality over time through software upgrades. While it wasn't big on my list of features I saw many comments in Head-Fi threads about the AK240 where people desired finer grained ability to sort lists presented in different ways. The AK240 currently doesn't have a lot of control over list sorting. I thought they were interesting comments though, and I suspect it's exactly these types of issues (things that people comment on) that Astell&Kern are looking at when developing ongoing software updates to the player.

I've set my AK240 to connect to my wi-fi on start up, and twice now I've received notifications of a software update available on the device. In both cases it was knuckle-head easy to push the button and let the AK240 reload it's brain and get a bit smarter. Didn't notice any changes the first time, but the second time I did see a "line-out" button appear on the volume control screen. Made me feel like I have a product that's just going to keep geting better and better.

Okay, turn the page and I'll talk about my two favorite things about the AK240: its user interface, and the sound quality.

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ARTICLE CONTENTS

COMMENTS
metaldood's picture

With Spotify and Google Music, it's hard for me to justify $2500 for a PMP. How often does one listen to PMPs? 2 hours everyday during commute? Phone + microSD + USB Dac is a good solution at fraction of the AK240 price.

Tyll Hertsens's picture

As I said right from the start, the AK240 isn't for most people.

But for those with a/the y/Yen, go for it.

iTroll's picture

My $140 USD was Colorfly CK-4 in 2011. In 201o, for about the same $$, I got a Teclast T-51 (that has two Wolfson DACs stock).
On head-fi, Player.ru and countless Chinese forums/blogs, modders have souped these and other DAPs to better-than-stock performance.
That said, modding, going thru threads to find bargains, etc. takes time. TIME = $$. So maybe AK's got the solution ... I'm sick of soldering-iron fumes, anyway ;)

Tyll Hertsens's picture
There are plenty of alternative to get good sound at a low cost. Heck, a Sansa Clip+ is damned good. That said, no one makes a player packed with this many very cool features performing at this level.
NickS's picture

I agree. I've been sorely tempted to get this or the Light Harmonic Wave, but I keep reminding myself that I mostly listen to Spotify these days, especially when I'm away from my home system.

Someone show come out with a portable audiophile Spotify player. (Spotify is compressed, so it is not really "audiophile" quality, but the paid version sounds pretty darn good.)

TMRaven's picture

What lousy industrial designer did Astell and Kern hire to design the aesthetics of this piece of shit?

TheAudioGuild's picture

Hey, it's got carbon fiber on it! It's gotta be cool!

Jazz Casual's picture

I wouldn't go that far but the design doesn't appeal to me either. I prefer the look of the AK120.

NickS's picture

The AK240 is actually quite beautiful when seen up-close, in my opinion. It does not photograph well. I think it is a brave artful design that is not going to be to everyone's taste.

Jazz Casual's picture

I don't doubt that it does look better in the flesh but I don't like the carbon fibre finish on the back of it either. To each his own as they say.

doublea71's picture

What a nuanced, thoughtful comment.

iTroll's picture

Who exactly are "Astell" and "Kern"? They can't be founders -- iRiver is a Korean company ...
Is just for snob show like ... posh-sounding Harrods, Lord and Taylors, Tiffany's, Abercrombie and Fitch ...
...ahem ... maybe Kim Jon Ill is outta da picture but I'd certainly buy a Dawewoo, Samsung, or worship the Rev. Sun Myung Moon.
LOL!!!!!!!!!!!!!!!!!!!!!!!!!

rhythm is life's picture

A graphic EQ on a $2500 DAP? That's lame. There's no excuse for that when you can get a parametric EQ for a number of DAPs out there. Of course, the target market for this overpriced lump doesn't particularly care for equalizers ;)

I thought the AK100 was overpriced enough when it came out. I was checking it out at the NY Audio Show last year, and I thought the build was solid, though the amp was underpowered. I asked the A&K rep about the EQ and he said he discouraged the use of the equalizer (wtf?) Like I said, the target market considers equalization to be audio blasphemy, though they don't mind using amps and DACs to color the sound of their headphones. Finally, I asked how much the AK100 cost. Well, I asked, and I couldn't afford it.

tony's picture

I hope there won't be a test tomorrow morning . How long did it take you to prepare for the Interface Video ? , wow , what a feature set !
Still , I suppose , all these features are important for a high level of music reproduction today , how am I getting by with only an iMac / Dac / Asgard 2 & a pair of headphones ? , this AK 240 demo makes me feel like my Mac is a Simple Record Player , phew .
Well , the future has finally arrived , we can now plunk ourselves down in the LazyBoy with a good pair of reading glasses and a AK240 ( which replaced that Rack of expensive HighEnd Electronics & Turntable ) to blissfully play all the Music the World has to offer , a nice pair of Roxanes or a nice little pair of Adam Acoustics , hmm , Nirvana ! Hide it in the Pocket so Wifey doesn't get suspicious about things Audio . It's portable too , isn't it ? , we can take it on a Flight can't we ?
It really isn't all that complex compared to my LG Phone or my Salesman's iPhone / iPad system , so why not ? $2,400 hmm , probably $1,200 next year as the competition heats up .
Does AK include a SD Memory Card organizer , I have to do keep my Camera Memory Cards organized too so I can envision a Memory Card Wallet system ( a leather thingy , bi-fold , fits in a shirt pocket or Purse , lots of colors to choose from .
Beam me Up Scotty , I'm jointing the 21st Century .
Nice Review , or should I say : Another nice Review !
Is that thing on Long Term Loan ? ( just kidding , from the last noisy postings )

Jazz Casual's picture

What's so raucous about asking a reviewer who has given a product a glowing review how he or she came to receive it? Of course, if you're a fat-cat who leaves questions of business ethics for your lawyers to answer on your behalf, then I can understand where you're coming from.

tony's picture

Tyll got a Loaner preloaded with Hi-rez files , he'll have to return it ( he kinda said that somewhere ) . The thing with Tyll is that he's trustworthy , which is why I ( and probably everyone else ) read his writings . If people suspect the integrity of someone they don't need to listen to or read what they say or recommend .
On the matter of "Glowing" I might substitute the word "Analytical" , Inner Fidelity is about the Science not the Sizzle ,
here I can agree that there are plenty of other sites that sell the sizzle , one wonders about those reviewers motivations but I rather suspect that sizzle is all they are capable of offering : In my Industry we call those people "Sizzle Salesmen" , they've mastered the emotional side of presenting and do quite well , that guy that sells Kitchen Gadgets on TV may be a good example .
I am not an Impulse Buyer , I need to see the Facts , this site presents in a Scientific format where 2+2=4 , here the science trumps the sizzle . Our Tyll is a Scientist , an Analytical despite his Hawaiian Shirts in the Frozen North or his Childrens red Tool box ( a nice Gerstner for $500 would be a much better backdrop , hint-hint ) .

Oh , Speaking of Fat Cats , did you know that Obama Care was actually designed by Republicans ? , it's really Romney Care , he originally designed it , it's quite a success in Mass. where Romney was Governor , he implemented , road tested and proved it's success quite a while ago . ( who knew ?)
So , Jazz Casual , thank you for your note .
Tony

Jazz Casual's picture

@ Tony - just to be clear, the discussion was about reviewer ethics in general and not Tyll in particular. I've been visiting this site since it's beginning, so I think that speaks for itself. But again, just to be clear, I wouldn't be coming here if I didn't respect Tyll's opinion.

I don't see what the introduction of health reform measures in (presumably) your country has to do with this topic (we've had universal health care in my country for more than thirty years by the way) but your comment has been noted, for what it's worth.

tony's picture

Yes , I agree , thank you . We tend to need reviewers now-a-days considering the Retail Environment moving to Internet based , we seem to no longer have a local Steve Guttenberg to offer sensible advice on these technical items .
By the way , your English is excellent and reads North American , sorry for my error in thinking you might be USA where the Elephants are unethically stepping on the little people by trying to shut down their Health Care access , many of us USA citizens are working hard to catch up with your socially responsible Governments , thank you for pointing the way .

Jazz Casual's picture

English is our language here too; a consequence of being colonised by the English. ;) Unfortunately, the current conservative Federal Government is trying to wind back our universal health care system by creating a two-tiered arrangement, along with introducing a raft of other socially regressive policies that will further disadvantage the poor and the elderly. I'm hoping they'll be thrown out at the next election. Anyway, back to head-fi related matters.

tony's picture

If we can afford Bullets we should be able to afford Aspirin ,
I think Winston Curchill said that and I still agree .

iTroll's picture

Hopefully there'll be a techno trickle down ... AK240 --> two years ---> AK47 ... and REALLY make it 5x cheaper.
Yupper ... I'm Umerruygun ... luv my GUNs.
My earlier comment about soldering and DIY ... so TH ... what's with that solderin' station and red toolbox in your STUDIO? Hardly seems thematic for Astell ampersand Kern ... you need to move into a ...

...and throw on an effin' suit and tie will ya!! ... caint figger out that Tropicana shirt thang you gots goin' on ... I mean you live in friggin' freezin' Montana for Chrissake.
At least you combed your hair, prettyboy!

Seth195208's picture

Attentention starved jerk? Just a little bit maybe?

sszorin's picture

Keep your toolbox open; AK240 would give you no respite from soldering fumes because it needs modding to be useful and to sound better.

NZtechfreak's picture

As per usual a very good read, thank you. Still deciding if this is something I would really use, generally for portable use I'm a little less demanding than when setting down at my desktop rig (Vega/Taurus-->HE-6), I'm pretty satisfied with my Galaxy Note 3 w/256GB full size SD + Dragonfly 1.2 + NAD HP50...

A little constructive criticism: this is a bit more littered with typos than I'm accustomed to here. Also, what happened to the images? They are of lower than usual quality, looking like smartphone shots taken in lower light conditions. Surely a piece of gear like this wants some nicer glamour shots?

SonicSavourIF's picture

as others in the comments have done, but experts like NwAvGuy, Sean Olive, Ethan Winer and many others have shown that it is absolutely possibel to design fully transparent and thus finest hifi gear without spending a lot of money. I'm certain that a similar performing DAP could easily be designed at a fraction of the cost. This is by no means justifiable.
Likewise it hase been convincingly argued that hi-rez files add absolutely no benefit (exept for dynamic range when you add bits, which you don't need for audio playback) but instead can degrade the audio due to IMD in case your sampling rate is too high.

I start to loose interest in the hobby due to inceasingly diminishing rationality. People seem to WANT to pay exceeding amounts of money. I just don't understand it. It was a huge relief for me to learn that it is not necessary to spend these crazy amounts of money to achieve perfect sound. I already have it.

Instead of one AK240 I will save up and eventuallu buy a hand made guitar wich starts at approximately 5k.
http://gropius.de/item/kleines-jumbo-modell-baujahr-2005/
This thing will last a lifetime and will be a continuous source of
joy. Devices like the AK240 will eventually break.

Pick your choice.

ubercore's picture

Hifiman used to sell a cheap balanced adapter for 2.5mm headphone jacks. They came with the re-zeros I bought. I didn't see it on their store anymore, though.

Tyll Hertsens's picture
As I recall, the HiFiMAN pinouts are different then the AK240 pinouts.
agoeldi's picture

Thanks, great review (as always).

Just to confirm your favorable impression: I bought an AK240 over three months ago, and I couldn't be happier, even considering the pretty outrageous price tag. It has completely replaced my home rig (Cambridge DacMagic Plus, SPL Auditor, Macbook with Audirvana -- with cables and power filter about the same total price as the AK240) because it's not only much more convenient but also sounds better. Detail resolution, soundstage, dynamics, mid range clarity, everything is noticeably better on the AK240. The only thing were the home rig has a slight edge is in the last tiny bit of bass punch.

The difference to more affordable mobile solutions (e.g. Fiio E17, Astell&Kern AK100) is so clear, it's not even funny. It's hard to go back to something simpler once you get used to the AK240's quality.

However, my favorite headphones are relatively easy to drive and quite analytical (Ultrasone Signature Pro, AKG K3003). This seems to be the sweet spot for the AK240. My Sennheiser HD650, which is a bit harder to drive, still sounds great, but the difference to other sources is a bit less pronounced.

For people who are more interested in high quality music reproduction than audio hardware tweaking, the convenience factor of having a single mobile unit is not to be underestimated. It's quite a treat to have a high-end system with a large music library in your pocket wherever you go. Even at home you can listen wherever you like and not just where your audio equipment happens to be.

Is that worth the huge price tag? It is for me. Honestly, I was expecting a major case of buyer's remorse when I bought this thing ("OMG, did I really just buy this?"), but that hasn't happened. No other device has ever improved my music listening experience in a comparable way.

TheAudioGuild's picture

Using the balanced output did deliver more gain (generally balanced outputs will give about 6dB more gain than unbalanced for a particular device) and did net a slight improvement in sound quality...

Slightly louder is perceived as higher quality. An old trick exploited by unscrupulous audio salesmen.

(I feel most balanced outputs improve quality due to increasing channel separation by ridding the headphones of the common ground between L and R channels).

I feel it's for the reason above. Otherwise, "balanced" wouldn't work with open back 'phones whose crosstalk would totally swamp what miniscule crosstalk is coming from from the common ground contact. In fact, I have doubts that the crosstalk from the common ground contact would even be audible.

Perhaps something you could put to the test.

tony's picture

Oh my , you are very close .
Balanced is Pro-Audio ! , the working Professional Music people rely on Balanced , long runs of cables , noisy environments , sturdy connectors , sturdy cabling , can't have noise creeping into one of the Channels .
For us civilians Balanced is nearly pointless except it allows us to use Professional stuff ( which is usually higher quality ) .
Pro-Audio people are big consumers of the Best Headphone equipment so the Manufactures like to feature balanced in their designs , a Professional is comfortable buying Balanced and sees the need which for us regular consumers doesn't exist .
The Test you request was done back in the 1980s when Meridian started offering their Active line of Loudspeakers which featured both Balanced inputs and a simple RCA input . Back then we established that the Unbalanced input with a Brisson interconnect consistently outperformed the Balanced Cabling systems Sonically , however , the lossy coax cabling runs limits to about 50 feet whilst the Balanced Cabling allows hundreds of feet of Cabling runs and tends to not be susceptible to electrical noise like what you might find at a CES Show Room or Music Venue where a good quick set-up is required and relied on . Robust Balanced Cable systems will never feature the articulation of a Tuned Cable from Transparent or Brisson sooooo , unbalanced can yield much greater potential sonic performance .
Congratulations , you probably just started a whole ton of Head scratching . It's a good topic for general discussion , certainly it's widely mis-understood if understood in the slightest by the headphone community of consumers .
By the way , who is the Audio Guild ?

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