Astell&Kern AK100II High Resolution Single DAC Audio Player

The AK100ii is a DAP I've had my eye on for quite some time. At first glance, it's obvious that it's a premium piece of kit, with it's clean efficient lines, quality touch screen, minimal physical interruptions, and compact size. Reading up on it's specs and the fact that it keeps (and improves) on it's previous iteration leads one to believe that for the asking price, this should be a one stop product, where a bunch of tweaking, additional cables, outboard DACs or amps shouldn't be necessary.
 
And ya know what? It lives up to the hype.
 
The Hits 

1. Support for every lossless format under the Sun
2. USB DAC capability
3. Wi-fi and Bluetooth capabilities
4. Smoothest, most natural UI I've encountered

 
The Misses

1. Physical button layout
2. FILE TRANSFER FOR MAC USERS

 
My Thoughts
 
To give you an idea of where I'm coming from, my head-fi DAP history has included a plethora of iPods, a sample of Sansas, a cache of Colorflies, a basket of iBassos, and a few Fiios. Some like the iPods, C3, and DX50 were used with additional amps & DACs, while the X3, X5, and DX90, have been standalones. 
 
For a while, the X5 was my go to as it checked off just about everything on my list. After all, most of my music is redbook quality, my main headphones are very easy to drive and I have no desire to have to carry a giant stack of gear around. Portable audio should be portable after all! 
 
Sound
 
The X5 never left me feeling like I was missing much on the sound end of things, but when a nice deal on a secondhand AK100ii came up, I pulled the trigger. Figured if for whatever reason, I didn't like it, I'd be able to move it along quickly. After giving it the full run-through with my RS1, GH1, and 1+2 however, there's no doubt in my mind that the X5 has been usurped.
 
Starting from the bottom, the bass is truly and completely audiophile quality. There's no bloat, no over-the-top sub-bass, and no Earth-shattering mid-bass lift (unless they're already in the recording). What I'm hearing is bass that is incredibly textured, articulate, fast, and dynamic. When called for, it can certainly bring the rumble, but that's only when I'm listening to hip hop or EDM which have that sound in the recording. The AK has made me realize that the X5's low end was a little warmer than I realized, perhaps to strike a happy medium between the budding audiophile and average consumer. 
 
In a word, the midrange is... neutral. I'm definitely a mid-centric listener. My entire desktop rig is designed around the RS1's incredible midrange. And while I loved the thick and lush vocals and crunchy guitars that the X5 gave me, going to the AK has shown me that I was losing out quite a bit on texture and depth. The 100ii doesn't just rush voices to the front of the mix. They stay a little further back so they sound more cohesive with the rest of the track, rather than isolated  to give them the spotlight. I'll admit sometimes I miss the warmth that the X5 lent to Norah Jones and John Mayer, but I think what I've gained in my upgrade is easing my suffering 

 
Treble. Clean, airy, textured, and sometimes, a touch too clean. If there's one sonic characteristic about the AK that gave me pause when I first received it, it was the upper end. It's incredibly uncolored and detailed. A clear step up from the X5 and the DX90. However, every once in a while the Grados and the Tralucent would get a little abrasive on abundant cymbal crashes or peaky female vocals. I added just a bit of EQ and rolled some foam tips onto my IEM's and now we're good to go. Now bear in mind, I'm a little treble sensitive, so fear not, I'm not saying that this headphone is nails-on-a-chalkboard screechy at all. It's overall presentation is very clean and neutral. It's gonna give you what's on the recording. If you've got treble-happy headphones, they're not going to be tamed. And if you've got warmer cans, the extra clarity on the upper end may be a nice synergy for you! YMMV.
 
With regards to soundstage/separation/depth/etc. the AK is the best I've heard in a portable solution. This is where I feel like DAP's really separate themselves and the AK shows that it's clearly a force to be reckoned with. Because of that ultra-clean treble, instrument separation is excellent; leaps and bounds ahead of anything I've heard from Fiio or iBasso. Soundstage width is only a little above average, but depth is quite good! The 100ii really shows off how capable the 1+2 is in this regard. 
 
Function
 
I don't care to spend too much time in this section because frankly I don't need to. I read a post recently about how a company choosing to employ the computer power of something of this caliber should make the UI almost cell-phone like and I agree... partially. If you're trying to market a premium product, IMHO premium sound is only half the battle. A premium UI is the other half. Luckily, the Android-based UI that AK has developed is very straightforward and easy to use. Granted there have been several firmware updates and as far as I know, they are still continuing to improve, but mine is running 1.25 and I don't feel like anything is missing. Menus are intuitive, controls are easy, there is minimal lag, and I've yet to experience a freeze or crash. When I rolled with the X5 and the DX90, I could navigate well enough, but I definitely felt like the UI was an afterthought. 
 
The only real qualm I have with this player is the file transfer protocol for Mac users. You have to download an app called Android File Transfer and quite frankly, it sucks. It's inconsistent. It's slow. It often hangs up. And it's incredibly limited in it's capabilities. Makes a new DAP owner a little bummed that he's got to try half a dozen times just to get his music on his player! Would love to see this little feature fixed either on AK or Android's end. 
 
I should also mention that the 'extra' features that AK chose to include are well-done EDIT: ok and appreciated. These include wi-fi capability for streaming, Bluetooth for wireless play, and USB DAC functionality that works very smoothly. The only one I really wanted was the USB DAC, but now that I have the others, I'm certainly feeling like I got more of my money's worth.
 
EDIT: Went back to further confirm these and didn't have a lot of success. They worked, but were a little inconsistent. Luckily for me, I don't use either of those functions very often.
 
Conclusion
 
In summary, the AK100ii, a.k.a. The Gatekeeper (for the land of portable high resolution listening) is a very well-made and designed product that anyone (that's ready to pony up for it's asking price) should consider. Now that it's been out for a while, firmware is very solid, and finding one on the used market makes it even more affordable. 
 
If you want neutral, clean sound with a slew of extra capabilities, then the Astell & Kern 100ii should be on your short list of players!

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Disclaimer:
 

I was provided with a free sample of Astell & Kern's DAP for this review by a local distributor.

 
Introduction:

Because of a small series of lucky coincidences I found myself on the phone with the CEO of AudioTuning, Austria's biggest audio distributor, and after a few minutes I got offered to review the AK100 II, which couldn't be declined. How often do you have the opportunity to test one of the best DAPs?
A week later my review package arrived, right after I finished my time with FiiO's second gen. X5, and at the moment this was the best sound I've heard. This was about to change very soon.
 
The box delivered what I knew about A&K. Elegance, style and absolute high end quality.
The AK100 II is the very first touch device I've used for more than just a few minutes, and it is the first I felt comfortable using, more on that in the UI section.
 
Its heart is Cirrus Logic's CS4398, the same as in the AK120 II and AK240. But the AK100 II only uses a single DAC chip. The battery has a capacity of 3150mAh, which gives the device power for about eight to ten hours. It features WiFi and bluetooth streaming.
The AK100 II has 64GB of NAND storage, which can be accessed via MTP from every Windows, Mac or Linux computer. Only about 56GB can be used for storage though.
Firmware upgrades are available through WiFi/OTA (OverTheAir). My device was running firmware version 1.12, later on the upgrade to 1.25 was released.
 
Headphones used:
Final – Sonorus VI
Final – Heaven VII
Pro-Ject – Hear it One
 
other gear used:
Cambridge Audio – Go V2
Pro-Ject – Stereo Box S + Speaker Box 5
Self built laptop running OpenSUSE 13.1
 

 
Package and Accessories:
 
The box comes in a matte black cover, which already screams premium from every corner. After the cover is slid off, the main box comes out. Again, everything from Astell & Kern is designed to remind you that you don't have an everyday DAP in your hands, this is how high-end feels like. And on every removable content, even on the mSD slot covers, there's the logo of A&K so you don't forget who brought you this experience.
 



The opened box brings out the AK100 II. Here it is. It's lying there peaceful and waiting to be discovered.
Under it is the box with all the accessories. What you get is a gray leather case for the DAP, a protective film, a mSD card slot cover (one's already inside the slot), a micro USB cable for charging and data transfer, a warranty card and a quick start guide. The screen has a protective film pre-applied.
 






 
Content summery:
 
AK100 II
Gray protective case
micro USB cable
two mSD slot covers
protective film for the back
Warranty card
Quick Start guide
 
Build:
 
The AK100 II is completely made of aluminum, only the back is covered in clear plastic. You will definitely feel its weight of 170 grams in your hand.
The front face of the device is nearly completely used for the 3,3 inch AMOLED touchscreen. Which is readable without any problems, the screen brightness can be easily adjusted with a swipe down from the top. The player feels great in hand and its size is perfect for one hand navigation. I can reach every corner of the screen with my thumb and my index finger takes over the volume control.
 
On the left side of the AK's body are the three hardwarebuttons for play/pause, previous and next track. Also the mSD slot is found there.


On top there are two jacks. A regular mini jack for phone/optical out and a 2,5mm balanced out. Next to the balanced out jack there's the powerbutton. The only thing on the right side of the device is the volume control wheel, where you can set the volume in 150 steps.


 
On the bottom there's only the micro USB port for charging, data transfer and USB DAC function.

 
One thing that could use some work is the mSD port, it is really hard to insert and extract the card, since it's pretty deep in the device. I almost always used a second mSD card to get it in/out.
 
iriver really pulled the design. It is the best looking DAP I've seen so far. It's not bulky or unhandy, yet beautiful and unusual stylish and at some point I felt under dressed.
 
User Interface (UI):
 
The UI is based on Android, and definitely the best one on the market. Only Rockbox beats the AK's interface. It is designed to be very easy and intuitive. Every content is reachable with your thumb, which makes navigating very simple.
The AK100 II will let you search your songs by title, artist, album, genre or playlist. You can also search your database with the songtitle directly or sort your songs by quality (All, MQS, DSD). Or you can easily access your songs by folder view.
It features a wonderful playlistmanagement, where you can simply add artists, albums or single songs to the current playing songs. Or you can drop them into an existing playlist or create a new one.
The home button brings you back to the main screen with a short press.
With a swipe up or down over the cover art you can either play the next or previous song.
If you go through your library and swipe down the screen the UI will show a scrolling bar on the right side of the screen for you to go even faster. A wonderful feature for huge playlists and databases.
A swipe down from the top brings you all the quick settings you need. You can easily access the most important settings. Turn on/off wifi and bluetooth. Change from MTP connection to USB DAC function. Activate the equalizer, gapless, balanced and line out. Set the play mode and brightness. It also shows you the most recent and important notifications. In the upper right corner you can access the settingsmenu. If you long press WiFi, bluetooth or EQ you can move to the corresponding screen.
One thing that caught my eye was the equalizer. It's a ten band EQ, which features two presets, Pro (settings as recommended by professionals) and AKT5P (for the headphone with the same name, made by beyerdynamic), these can not be modified. But you can also add custom EQ curves by adjusting the frequencies of the 10 band EQ. I hardly use it, but when I do I create customs for my headphones instead of genres. That way I can fine tune my cans to the desired sound.
The top part of the screen is the notification bar, which shows you what's currently enabled, e.g. shuffle, Line Out, WiFi, bluetooth, battery percentage, time etc.
The only things missing in the firmware are replaygain and putting songs in queue, there is a feature, only sensible imo when playorder is not set to shuffle, to move songs around in the playlist.
Also there's only one bug in the software, the device never remembers the USB mode settings. I always had to set it back to DAC. Luckily the UI was well designed and the quick settings are accessed extremely easy.
 

                 UI with firmware 1.12                                                              UI with firmware 1.25
 

   Quicksettingsmenu open with a swipe down from the top                          Now playing screen
 
Changes of the new firmware (1.25, released August 18th) which should get reverted in my opinion:
- long pressing the home button brought you back to now playing before, disabled now.
- the ability to draw EQ curves for a fast and easy way to add custom settings
- home screen now takes up way too much space, the buttons were already very well designed in the previous firmwares.
- for faster scrolling the bar on the right side (in database) used to be an alphabet, to get you to a specific letter.
- USB DAC makes audio out of sync, very annoying!
 
 
Bluetooth streaming:
 
The AK100 II also supports bluetooth streaming to portable speakers or wireless headphones. It comes with bluetooth V 4.0 and no aptX support.
The bluetooth streaming option is recommended for any file format up to 48kHz, any higher resolution files may stutter. And I tested that too, it did.
I tried streaming different high-res (96-192 kHz) files to my Cambridge Audio GO V2 and all of them had hiccups. Everything below 48kHz was fine.
It will be a long way until bluetooth streaming will get close to the quality a wired connection offers in my opinion.
 
USB DAC:
 
At first I was a little worried that it won't work as USB DAC since I've read that a few Mac users had problems connecting the device with their computers. But all worries have stepped aside as soon as I tried it out myself.
I only use Linux machines, and never have I had any problems using the AK with either my laptop or my PC. Everything works out of the box (with pulseaudio en- and disabled).
Unfortunately the highest supported format is 24/96, so everything above that will get downsampled.
The new firmware also changed the DAC function, and not in a good way. When using the AK100 II as DAC and watching movies you'll definitely notice that it is out of sync! The audio is about half a second late, and this is not what you expect from a 1200€ device. VERY DISAPPOINTING!
 
@Limexx found a fix for Windows machines:
 
1. Right-click the speaker icon and click 'Playback devices'
2. Double-click the AK100ii
3. Go to advanced
4. Unclick exclusive mode
 
So far I couldn't find a global solution to this problem for Linux/Mac users.
If you're using VLC you can easily fix the synchronization by pressing J or K while the video is played, but the delay's still present with any other content (e.g. youtube videos)
 
Sound:
 
iriver does not want their players to be in the same boat with the others, that's why they call their DAPs “Mastering Quality Sound Portable Systems”, and that's what they are.
I have heard FiiO's new generation X5 because I also wrote a review for it. I was, and am, really impressed with the sound that comes out of it, but the AK is a whole different league. It makes the FiiO sound muffled and very analytical.
 
The AK100 II has a huge and super realistic soundstage with the best image I've experienced. It's unbelievably balanced and neutral. In fact it's the most neutral sound I've heard coming out of any device, desktop or portable. It has a great vivid body and a lot of air between the instruments. Its attack, decay, sustain and release are very impressive. It also has a very black background. Every frequency gets delivered fast, crisp and super precise with outstanding instrumental separation. This is how it's supposed to sound like, true mastering quality.
The firmware upgrade was very noticeable in sound. It made the device sound even cleaner, wider, more natural and precise.
 
The AK100 II makes any other DAP I've heard sound boring and blurry, and I don't know how to go back to the X5 now.
 
I tested the AK with three different headphones. Pro-Ject's Hear it One, and Final's Sonorus VI and Heaven VII.
 
The Hear it One has a wonderful soundstage for a closed back headphone, it sounded great, a little warm but over all very well defined. Highs are very sharp while mids come along very smooth, bass is overly present for my taste. Listening to Jazz recordings, especially Dave Brubeck's Time Out in DSD quality, with this headphone was the best combination for it. Trumpets, Snares and Basslines sound very natural and smooth.
 
The Heaven VII shows more detail and better soundstage, also more neutral and natural. The highs are this headphone's strongest point. You can almost feel the strings and triangles. Also the bass lines appear clearer and more lifelike.
 
The Sonorus VI are definitely the best headphones in this comparison. The soundstage grew again from the previous phones. Overall the sound is more vivid, precise, neutral, detailed and natural. This is the best setup in my home for the AK100 II. It also was my main combination in the time I had the AK. The sound showed astounding microdetail and instrument separation I can not compare it to anything I have heard so far.
 
I think to enjoy the AK's full potential you should listen to it with proper headphones, even though it brings out the most of the lower end cans, you will experience something amazing with better iems/headphones.
 
Conclusion:
 
The AK100 II is the whole package. You get incredibly beautiful design, the best user interface and addictive sound. But you have to pay a lot of money for that, if it's worth it is yours to decide.
The lag in DAC mode's a huge disappointment, I really hope Astell & Kern/iriver will fix this with the upcoming firmware, it worked perfect with the previous release.
 
Currently you can get it for $899 or €1199.
 
 
Final Words:
 
Again I would like to thank AudioTuning for providing me with a sample of the AK100 II for this review. It was an unbelievable experience.
With a heavy heart I have to send it back now.

If you have the chance to audition an Astell & Kern, do it, but remember, their sound might not let go of you.
 

Whereas I am also an old school hard-core vinyl aficionado, I (luckily) jumped the digital high-res train early enough to nowadays be equipped with the most necessary hard- and software to be able to really enjoy that playground.
 
After the rise of CDs in the early 80s I started to examine the options with Sony’s SACD as soon as it became available on the consumer market. And to a certain degree I still use SACD. Namely the SACD plugin (…or “add-on” or whatever…) for foobar2000 to play DSD via my ifi micro iDSD.
 
Concerning portable high res, earlier I “played” around with the AK100 (MK 1, the one with the rather high output impedance), I own a FiiO X5 and I had a loaner X1 for testing. I also use the Onkyo high res App for iDevices, but I am not sure whether this really brings high res to the output, or whether it downsamples to easier processing 48kHz/16bit… I’d rather guess so since when I compare higher res flac with wav on my iPods I frankly cannot hear a difference that could not also be created just by using a different player software / algorithm.
 
Design (Hardware)
 
First thing I need to mention: The design. I am a design fetishist and this passion certainly is having a share in triggering my purchases. Well, in the case of the AK100II I have to say: Close to perfect!!!
 

 
The AK100 Mk1 simply didn’t have the proportions. Also the weight didn’t fulfil the expectations I had towards a high end player. Sure, lightweight can be an advantage for mobile usage, but my haptic senses were absolutely not satisfied holding it in my hands.
 
The FiiO X5 & X1 come along somehow too “martial”. Especially the X5 could be a kind of a 1990s military walkie talkie design study. Well, there will be those who appreciate that.
 
Back to Astell & Kern. Even within the actual AK product range the AK100II is my favorite design.
 
To me the AK120II has a too high forehead (if you know what I mean)...
 

 
...and the stealth design of the 240 is just too much for me. Whether good or not, it is simply not my piece of cake.
 

 
So lucky me, that the one I like most is also the most affordable one, which surely made a purchase decision easier.
 
By the way, until today I simply reject to upgrade from my iPhone4 since I prefer its design to the younger versions by far!
Here a comparison of size AK100II to iPhone4
 

 
The AK100II feels great to hold in my hand, also the weight is what I expect. The sharp edges, the brushed aluminium surface and the postmodernist volume-wheel protection feature adds just the right pinch of spice to an otherwise slightly too reduced formal language.
 
Also the touch screen is the right size and well readable.
 
One of my conclusions from the X1 / X5 comparison was “Maybe the X7 will have a larger touch screen? …and WIFI (…)”
…and then the AK100II comes along and offers exactly this…
 
Design (Software / User Interface)
 
This leads us directly to the user interface. It is as nicely designed as the hardware.
Reduced to the minimum and necessary. Well readable. Self-explaining, just the way it makes it a joy to use it. This is actually one of the weak points of the FiiO X5. Harder to read, less comfortable to use and an issue with the volume buttons and skipping titles. All of that is by far better solved with the AK100II.
 
The “home button” integrated to the touchscreen is a very nice feature, and the volume knob a joy to use. It goes in 0.5dB steps. If you want to go faster you can also pull the spherical volume visualisation on the touchscreen for a convenient fast adjustment.
 

 
Sound
 
Anyhow, I actually preferred the rather hefty approach of the FiiO X5 compared to the AK100 Mk1. I also found the X5 more open and less coloured. But I have to admit that this might also have been owed to the fact that I had the AK100 Mk1 with the high output impedance and most of my cans are rather low in that aspect leading to a sub-optimal dampening factor. There was a Mk2 with a significantly lower output impedance but I never had the chance to hear that one, so now I have not the slightest idea how this (improved) AK100 Mk2 would stand against the FiiO X5 or against the latest AK100II.
 
But one thing is for sure, the sound of the AK100II plays in a different league compared to the X5; to be fair it is also in a different price-league. Who knows what the FiiO engineers would create with such budget given… but well, that’s another story then, maybe a X7…?
 
The first thing I recognized when auditing the AK100II was the openness, transparency and clarity of sound. It is so… “non-grainy” (…sorry, have no better word for that).
You might have guessed it, great detail, soundstage and separation of sound-sources are a direct result of such precision. I guess with this everything was expressed that is necessary to be said about the AK100II’s mid- and high-range.
 
What really surprised me was the bass, which is utmost precise and structured and as such goes perfectly well with mid- and high-range. But whats really great is the fact that it still has the substancial impact I expect.
I experienced with a lot of other equipment that precision of bass had to pay the price of lacking impact. Or the other way round, bass impact came together with a loss of contour. Not so with the AK100II. Here it just sounds right.
 
I just now listen to Symbion Project “Pawn To King 4” with the LCD-X. Wow, clear, fast & deep going along with the necessary impact and pressure.
Earlier today it was Philip Glass’ Akhnaten, Rush Moving Pictures and Thievery Corporation. All just as I like it.
 

 
Obviously, since the LCD-X is driven with ease, also the less demanding AH-D7100 and AH-D600 go very well with the AK100II, and my Monster Miles Davis Trumpet are plugged in anytime I use it mobile in the subway or whatsoever.
 
So I actually listened my digital music collection randomly up and down with the AK100II; and this I must say was a quite joyful trip...
 
The 7100 I do not use for travelling, the loss would be too high if lost…As such, for travels and hotel listening I will prefer the combination AK100 with AH-D600. Together with the short Denon cable for mobile usage this sounds simply fabulous!
 
Conclusion
 
I would call the overall sound signature “neutral”, but not the “dry” style of “neutral” which is in so many cases associated with the term, no, it is the natural aspect of neutrality. It simply sounds naturally neutral. Yes, that’s it!
 
Comparing the balanced and the un-balanced output with the SE535:
As expected the sound signature remains the same. Also power-wise I couldn't say that this makes a significant difference because the SE5535 obviously doesn't need a lot of it.
 
Still, the bass is now even slightly more structured and transparent (...I was surprised that a "more" was still possible...) and there is a hint of more open mids resulting in a marginally larger soundstage.
 

 
I didn’t try the streaming- nor the DAC function. I have great dedicated units for that, and I do not want to bother to connect it back to the main rig anytime after I used it mobile. So no use for me to really look into it.
 
So far from my side; a double thumbs up!
 
All I would have wished for is a slot for a second Micro SD card (so here X5 has a point; it can take two 128GB solid state drives)...
 
Cheers!
 
PS.: So what happens with my X5 now? It remains in my main rig as a digital High Res source, feeding the DAC there via coax cable… Here it is just perfect with its 256GB. As such I have a classical win-win situation  
 
PS: At the moment this is my most favorite portable combination: The AK100II with the AH-MM400:
 

 
More pictures here.

Astell & Kern AK100 II: Portable Pleasure
 
So I have a confession to make: I’m a DAP “noob”. I’ve basically been old school with my on-the-go Hi-Fi, using iDevices and a third party amp (HeadAmp Pico, RSA Audio Hornet, et cetera…) or even an Amp/DAC combo like the Beyerdynamic A200p. Then I tried the Astell & Kern AK100 II. While I’ve heard some lower priced DAPs, I’ve never felt the need to reach outside my iDevice/external amp setup. That is of course until I got to review the AK100 II.
Astell & Kern is a division of iRiver and based out of South Korea. The company offers three high end Digital Audio Players (DAP): the AK100 II, AK120 II and their flagship, the AK240. These are all serious “high-end” products. The AK100 II is the successor to the already popular and highly respected AK100. The updated verision utilizes a DAC chipset (CS4398) by Cirrus and a dedicated amplifier that outputs 2V in balanced mode and 1.7V in unbalanced mode. Though I would have liked to see a balanced adapter included with the player, one can still purchase the adapter separately.

I’ve run IEMs (Shure SE535s), portable headphones (beyerdynamic T51p and Sennheiser Momentum On-Ears), and full sized headphones (like the Fostex TH900s, Audeze LCD-Xs and Grado PS1000e’s) with the AK100 II. All cans were certainly driven with authority by this little unit. The AK100 II is also WiFi capable, so you can use the supplied MQS Streaming software to stream music off your home music server. This is a fantastic aspect of the player and it allows you to stream your entire the music from your main server to your Astell & Kern DAP – giving you access to your entire digital library. The setup is simple and the convenience is much appreciated. Another added bonus is the ability to update the firmware wirelessly.
In order to increase your storage space from the supplied 64Gb, the AK100 II has a microSD expansion port for an additional 128Gb of storage bringing the grand total to 192GB. That is plenty of music to take with you and should suit your portable needs nicely. The AK100 II also can be used as a USB DAC and take the music off your computer and feed it to your DAP directly. 
 
The overall construction is solid! It’s made of a hairline and diamond cut finish for the aluminum body. While it’s not cheap, coming in at an MSRP of $899 USD, it does step up to the plate with fantastic build quality. The volume control knob is a stepped attenuator (something I really haven’t come across on portable DAPs) and each step is an impressive 0.5dB. So you will have the benefits of precise left and right SPL levels that a stepped attenuator offers with the added bonus of 0.5dB steps to get the listening levels exactly where you want them (as with an analog attenuator). It also comes with a handsome carrying case to protect the unit.
The touch screen and GUI (graphical user interface) is quite intuitive and easy to navigate through. It offers a clean and simple presentation and accessing the quick menu is as easy on my iPhone (just drag downwards from the top and you can access Wi-Fi, Bluetooth, EQ, SD card safety removal, among other things).
Navigation is also well executed as the layout is simple and straightforward so you can easily find your favorite artist, album or song. And going back to the home screen is as simple as pressing the “Home” button on the bottom of the unit. Astell & Kern has obviously put a lot of thought and care into this fantastic operating system and GUI that is not only intuitive, but provides you all the functionality you may need while never being difficult to operate.
The battery life on this little guy is impressive. I’ve used it continually at work with my Shure SE535 IEMs for a solid week and only needed to charge it at the end of the week. This is on par with my iPod Classic (160Gb) and is certainly more than enough to keep me happy. It is rated for up to 12 hours of playback before needing to be recharged.
 

I’ve literally thrown every codec that I have at the AK100 II: Lossy MP3s, lossless music, high resolution 96 and 192kbps files, FLAC and DSD have all worked flawlessly. I didn’t even need to setup separate folders for each file as it was just copy and paste onto the AK100 II and then just press play. It was literally that easy. I definitely appreciated this simplicity of operation.
Sonically, I would classify the AK100 II as a clean and spacious sounding DAP with excellent detail retrieval. I wouldn’t call this a warm sounding unit. Don’t get me wrong, the bass is certainly there, but if you’re looking for a slower bloom, (a coloration in my opinion) then you might want to look elsewhere. But listening to Metallica’s “Enter Sandman” from the Black Album, the rumble down low is more than satisfying with my Shure SE535s or Beyerdynamic T51p’s. They reach down to the lowest depths and offer a taught and quick bass that never lingers more than the recording calls out. However, I know some prefer a boomier bass with more bloom and if that’s what you’re after; then, I’d suggest you play with the EQ, which also works quite well and didn’t introduce distortions or artifacts during my trials. Accessing EQ was simple, just use the pull down feature to activate it and set the equalization to your preferences.
The one thing that initially struck me with the sound of this DAP is just how clean and open it sounds. The ability to render detail (and finer micro detail) is simply jaw dropping. I was mistakenly under the impression that one needed a desktop sized DAC / Amp to achieve this impressive level of detail rendering and sound staging ability, but it appears that the AK100 II is up to the task. There are always sacrifices one has to make with portability, that’s obvious due to plain physics, but with the AK100 II, I feel those sacrifices don’t have to be as large as I initially thought. Plus the ability to save up to a whopping 192Gb worth of data can mean you can also carry a good portion of your music with you and not have to only select the “Greatest Hits” albums in your collection as a compromise.
The treble extension of the AK100 II offers an airy and open presentation with outstanding shimmer and detail of the upper registers. As mentioned before, this is not a warm sounding DAP, but rather neutral and as such, the treble is not rolled off; however, it is neither strident, nor “bright”. When listening to Gustav Mahler’s Symphony No. 4, the flutes and sleigh bells sounded sublime with incredible detail that could compete with an impressive full sized rig. I couldn’t believe just how good both my SE535 IEMs and Audeze LCD-X full sized headphones sounded. The AK100 II was able to locate each instrument precisely in my mind’s eye with outstanding instrumental separation. The cast sound stage was both wide and deep. If I had to list the top item I was most impressed with this unit, it would be its ability to sound open, clean and offer top-notch imaging. I threw several other albums at it from Rush’s Moving Pictures, to Frank Sinatra’s Duets, to The Black Key’s El Camino, and it never once sounded closed-in or congested.

And the vocals are sublime. K.D. Lang’s Hymns of the 49th Parallel reminded me why she is one of my favorite female vocalists of all time. Listening to her sing Leonard Cohen’s “Hallelujah” or Ron Sexsmith’s “Fallen” was awe inspiring. The AK100 II kept up with this demanding recording and I can easily say that Lang has never sounded this good when on the go. Her voice was neither withdrawn nor pushed up front, but in almost perfect proportionality to the rest of the music. And thanks to the AK100 II’s ability to render an incredibly high amount of inner details, I was left imagining myself in the recording studio sitting right in front of her. I can only imagine how good the AK240 would portray this album considering how amazing it sounded with the AK100 II.
Overall, while not cheap by any means, I think the AK100 II offers outstanding value as it rivals some of the better and more costly desktop rigs (with a standalone DAC and amplifier) that I’ve heard. Throw in the fact that you can carry up to 192Gb of your high-resolution music with you and you can use this DAP as a standalone USB DAC with your PC, it’s a real winner for those who are looking for great sound on the go. The neutral and open sound signature of the AK100 II will grab your attention and never let go while you’re on the go.

I recently got the AK 100 II after dabbling with a phone based stack.
 
Alternate setup:
    Samsung Galaxy S5
    FIIO E18
    + PowerAmp Pro (Cost: 2.99€) + iSyncr (Cost: 3.99€) + Stream to Media Devices, BubbleUPNP (Cost: 3.49€)
 
Sound Quality for this setup is GREAT. Love the E18 and its performance and great sound.
 
 
I had bought the E18 so I could combine good music and being on the go with 1 "device".
After a couple of weeks, I found that a phone based stack is a bit cumbersome and not very handy.
 
So, after snooping though the forums for ages, reading up on features, sound, etc I saw that Astell and Kern released the new AK100 II.
The AK100 II was announced with most of its primary parts as the AK240 has, but a single line (so no dual DAC and AMP and without the dedicated DSD processor)
It runs on a proprietary Android version, seems to have a nice UI.
 
As we do not have any shops in Belgium carrying them ... I decided and went for a bind purchase from a great shop in the UK (I live in Belgium).
(http://www.custom-cable.co.uk/) Within a few days my new AK100 II arrived, I unpacked carefully but in a hurry ... curious to see, hear what I had bought.
 
First Impressions
The package I got from the shop in the UK was a quite large cardboard brown box. On opening the box I found an nice AK branded black box. The AK packaging is a nice even black with only the AK logo on it.
 
[Some pictures]

 

 

 

 

 

 

 

 

 

 

 
 
The UI [User Interface] is a smooth, easy to use. It has been made for non expert users, easy, few buttons, sleek.
 
Once I put some music on it I finally got to the listening part .... and what a PLEASURE that was.
Very clear sound, silence is silence, my library with a mix of classical -70%-, trance -15%-, bagpipe and jazz came to light.
Most of the tracks are in FLAC, in different levels of quality (16/44 up to 24/192).
 
I immediately tried my different headsets, BeyerDynamic DT880, AKG K551, Sennheiser Momentum, all performed great. The AK even pushed the BeyerDynamic DT880 250 Ohm very nicely.
The sound stage on the AK100 II is wide, pure and light. Never boring or flat.
 
I asked a colleague at work (a 'real' audiophile) to give it a listen.
He was using his shure 215's (he is the 'room' type audiophile, the shures are for at work).
During his listening he immediately noticed the very pure and open sound, more spacious. His comparison was the exact same audio file on his iPod to my AK 100 II.
(file used was: Buena Vista Social Club - 1997 from iTunes)
 
He was truly astonished that only the device could already make this big of a difference.
 
The software on the device comes with a great EQ for those who need it. Just draw the EQ line on the screen and the software matches the line you drew.
Again, simple and easy to use.
 
 
The only thing I would suggest Astell & Kern to add would be a good Sync Software so users can easily select what they want to Sync with their very nice AK devices.
I'm sure a collaboration with a good maker is doable ... why not with MediaMonkey of FooBar2000 community?
It would make our lives so much more practical.
 
You can of course just copy the files with Windows, but that is not hand and it is not really manageable.
Having Sync list 1 for weekends, Sync List 2 for work, etc could be very nice.
 
 
Small note: It work also great a DAC on my PC's!!!  
 
 
UPDATE [3-Jul-2014]: The AK100 II also works as DAC on my Samsung Galaxy S5, but via a OTG cable and not via simple micro-usb to micro-usb, it MUST be an OTG cable.
                                 Otherwise just Plug and play!!!
 
 
 
Well, that is it for me.
 
VERY, very happy with my new player!!!!
 
     - Compact
     - Great battery life (2 to 3 days at work, and you could add an external battery pack to recharge ...)
     - Great Sound with a wide sound stage
     - Great detail in the music
     - Excellent UI (bit slow with over 2400 songs + Album art)
 
 
With Kind regards,
 
Casper
A very happy customer.