Astell & Kern AK120 Portable Music Player Reviewed

Published On: August 8, 2013
Last Updated on: October 31, 2020
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Astell & Kern AK120 Portable Music Player Reviewed

If an iPod just doesn't cut it for you in terms of sound quality, you may be interested in the Astell & Kern AK120 portable music player. Steven Stone tests out the player to see how its high resolution performance measures up.

Astell & Kern AK120 Portable Music Player Reviewed

  • Steven Stone is the former editor of He a longtime audiophile and home theater writer, as well as a musician and recording engineer. Steven has written for publications like Stereophile, as well as,, and The Absolute Sound.
    Steven is plays guitar, mandolin, and Ashbory bass and is a collector of fine musical instruments.

AstellKern-AK120-portable-music-player-review-small.jpgWhen Astell & Kern introduced its first product, the $699 AK100, skeptics said that, in a world of smartphones and $15 earbuds, it would never succeed. To the consternation of naysayers, the AK100 proved there was a substantial market for an elegant high-end portable player. To add to an audiophile's portable player options, Astell & Kern has gone even further with its latest offering: the $1,299 AK120. What does the AK120 bring to the table to command such a price tag? How about more technical refinement, greater storage capacity, and more functionality?

Additional Resources
• Read more reviews of media players in from's writers.
• Explore more reviews in our Headphone Review section.

To a casual observer, the AK120 looks almost identical to its older sibling, the AK100. When you put the two players next to each other, however, you see that the AK120 is approximately 0.5 inches taller and has protection ridges around its slightly thicker volume knob. The AK120 also comes with a very nicely made leather case that fits snugly over its semi-gloss black metal chassis. This case isn't merely a $5 cheapie. I bought a similar case for the AK100, and it cost over $80 on eBay (the only U.S. source I could find!).

The AK120 supports a variety of digital formats and resolutions, including FLAC, WAV, WMA, MPR, OGG, APE, AIFF, ALAC, APE, and 64x DSD. Playing time varies depending on the file resolution. For MP3s, playing time is as long as 14 hours but, when playing high-res files, you can expect the battery life to drop some. The AK120 comes with iRiver's Plus 4 software for use with Windows XP, Vista, and Windows 7 computers. This software makes moving music between your computer and the AK120 relatively easy and more intuitive than dragging and dropping files into folders. If you plan to use a lot of 96 kHz, 192 kHz, or DSD music files, transferring them will be a lengthy process time-wise. The AK120, just like the AK100, supports streaming from supported Bluetooth 3.0 devices, such as an Android or iPhone when they are within a 20cm range. When a phone call comes through, the AK120 will automatically disconnect. While the Bluetooth connection will support higher-resolution files, the AK120 instruction books cautions that "high-quality" music files over 48 kHz may "slow down the products," so, to ensure optimal stability, 48 kHz and lower files are recommended for streaming, but files below 32 kHz are not supported by the Bluetooth protocol used by the AK120.

Inside the AK120 you'll find not one but two Wolfson WM8740 DAC chipsets. Each WM8740 is dedicated to a single channel, unlike the AK100, which uses one of these DAC for both channels. The dual-chip arrangement gets the AK120 an 8dB better crosstalk specification, 40 ps less jitter, and 3dB more signal-to-noise than the AK100. Controls on the AK120 consist of a volume knob sticking out of one side, three small buttons on the other that control play/pause, previous/rewind, and next/fast forward, and, on the top edge, a small button that functions as a volume lock once it has been activated. All other functions are adjusted via the AK120's touchscreen LCD display. The display contains multiple nested menus that keep a majority of the most-used controls on the main screen, but there is one adjustment that is buried four levels down called the "Volume Lock," which most users will want to activate almost immediately; without it, there's no way to ensure that the volume (and other controls) won't be accidentally activated while the player sits in your pocket.

Among its features, the AK120 offers two kinds of equalization. First there's "Pro EQ," which is a fixed equalization setting "recommended by expert" according to the AK120 owner's manual. No other info is available in the guide on what this EQ is actually doing. There's also a five-band equalization screen that offers up to 10dB plus or minus corrections at 62, 250, 1000, 4000, and 16,000 Hz. The EQ is meant primarily to correct for earphones that need help in some part of the frequency spectrum, but it can also be used to correct for a particular album or track's harmonic issues. For purists, the EQ function can be completely bypassed, which will also result in a slightly higher output level. My only criticism of the EQ is that the AK120, just like the AK100, lacks any EQ save-and-store functions, so you can't keep multiple EQ settings, such as one for each headphone you use regularly. Every time you change to a pair of headphones that requires new EQ adjustments, you must go into the EQ settings and change each of the five bands manually.

Features that differentiate the AK120 from the AK100 include the ability to hold 192 gigabytes of music, compared with the AK100's original specification of only 96 GB. The AK120's internal memory holds 64 GB, compared with the AK100's 32. Also, the AK120 supports two microSD cards up to 64 GB. When introduced, the AK100 only supported 32GB cards, but its latest firmware update brought its capabilities up to 64 GB (as well as adding gapless playback.) One of the primary reasons prospective owners would choose the AK120 over the AK100 is its USB DAC capability. Its Wolfson WM8740 chips can be used for digital-to-analog duties by merely connecting the supplied USB cable between your computer and the AK120, designating the AK120 as your default audio device, and playing music. The AK120 is a fully compliant USB 2.0 device that won't need any special drivers for Mac or PC operating systems. When used as a USB DAC, the AK120 supports files from 44.1/16 all the way up to 192/24 PCM and 64x DSD (if your computer's playback software supports 64x DSD). The AK120 can also serve as a DAC for SPDIF sources, such as CD transports. It has provisions to accept a Toslink input and has a Toslink output that can be used if you want to send a digital stream to another DAC. The only time the digital output is not active is when the AK120 is being used as a USB DAC, which is too bad, since it could be used as a USB-to-SPDIF converter if it remained active.

Accessories included with the AK120 include a special USB cable for docking, charging, and transferring files (don't lose this, as all the third-party cables I tried with the AK120 did not deliver full functionality when connected to my Mac), plus a quick-start guide, warranty info, an extra plastic screen and back protectors, an Italian-made custom leather case, a high-resolution music sampler from in its internal memory, and a black cloth bag to prevent scratches on the AK120 during transit. The packaging is slick but not overdone, featuring a matte-black box that slides into an outer sleeve. The AK120, unlike many "premium" products, doesn't waste money on over-the-top display boxes or unnecessary frills.

Read more about the performance of the AK120 on Page 2.

AstellKern-AK120-portable-music-player-review-player-alone.jpgWhen you turn on the AK120, be prepared to wait. From off or sleep mode, it takes 20 seconds for it to wake up and become
fully functional. Once awake, the AK120's touchscreen is quite sensitive and very responsive. The screen contains information besides the usual song title, artist's name, play, pause, rewind, and song timing. You'll also see the current time, Bluetooth connection status, battery strength, and access to sub-menus for navigating through your library, options, and even lyrics (if they were imbedded in the metadata). If you are a regular Apple user who is used to the vertical integration of Mac computers, iTunes, iPods, iPads, and iPhones, the lack of automatic synching and integration with your music library will seem primitive. It's not that the AK120 isn't Mac-friendly - it does "play nice" with a Mac once tethered via its USB cable - but all of the file functions (such as adding or removing tracks) must be done via drag-and-drop on a Mac. PC users will find that using the iRiver 4 software makes adding and subtracting music files more intuitive and less of a bare-bones operation. Even with this dedicated software for managing music on the AK120, it won't be as slick as the iTunes/iDevices' automatic synchronization. Still, anyone familiar with moving files on and off of external drives will find the AK120's interface easy to use and understand.

One control that you won't find on the AK120 is a mute button. Instead, when you need to cut off the sound, you must use the pause control that's located on the touchscreen. If you've activated the "Volume Lock" button, you will have to push it first before you can access the touchscreen to hit the pause button. A&K felt the loss in sound quality caused by a muting circuit was too great. While some potential users might be turned off by the AK120's minimalist approach to ergonomics, anyone whose primary focus is optimum sound quality will appreciate Astell & Kern's decision to optimize sound quality, even if it means a few less ergonomic bells and whistles.

The AK120's volume control has a numerical scale from 0 to 75, which relates directly to dB levels and allows for .05dB adjustments. I found the range suitable for almost every headphone I tried with it. The most sensitive in-ear monitor I have, the MEE Electronics A161P (110 dB sensitivity, 32 ohms impedance), used the 39dB setting, while my Beyer Dynamic DT-990s (600-ohm version) required almost the full output of 75 dB to play at a decent volume level. Unlike the Astell & Kern AK100, which has 22-ohm output impedance on its headphone output, the AK120 has more universally earbud-friendly resistance of only three ohms. This should make owners of especially impedance-sensitive multi-driver in-ear monitors happy. On paper, even the weirdest multi-driver in-ear monitor should have adequate bass without impedance-caused low-frequency roll-off.

Classical music lovers, as well as those audiophiles who listen to the Beatles' Sgt. Pepper's Lonely Hearts Club Band or Pink Floyd's The Wall on a regular basis, will love the inclusion of gapless playback in the AK120's feature set (this is also included in the latest AK100 firmware update 3.0). This feature eliminates the pause between selections so that listeners aren't subjected to the horrors of two seconds of dead space, which has been known to cause sensitive listeners to fly into catatonic fits.

The one and only ergonomic quirk I found with the AK120 was its sliding micro SD slot door. Unlike the AK100, where the door clicks into the open position and stays there, the AK120's door has no click and is loose enough that gravity can close it slightly. To change SD cards, you must keep the AK120 slanted so that the door will remain open during installation. Yes, this is a minor problem, but considering the AK120's otherwise excellent ergonomics, it's one that Astell & Kern should have addressed.

For some uber-audiophiles, the only thing that matters about the AK120 is whether it can deliver better sound quality than anything else available. Have no fear: with the right high-resolution source material, the AK120 easily delivers state-of-the-art sound quality. However, with most 44.1/16 commercially released music, whether from downloads or ripped directly from the CD, I found that the sonic differences between the AK120 and its less-expensive sibling, the AK100, were slight at best. To compare the Astell & Kern players, I set up a nice robust A/B test that you too can do at home. The headphone outputs of both players were routed to a nifty little A/B/C/D box, the HS2 ($25), created by FIO for comparing different portable players' headphone outputs. Once both units were connected to the HS2, I matched their output levels, put the same music files on both players and began listening. I used several headphones for my A/B comparisons, including the Audeze LCD-2, Grado RS1, and Stax 507 earspeakers (connected to the Stax SRM-006t amplifier). In every case, the differences between the two Astell & Kern players were minimal. With commercially available 44.1/16 files, such as Norah Jones' superb first release, Come Away With Me, I really couldn't reliably tell one player from the other. On some of my own live high-definition concert recordings, I could hear that the AK120 had a slightly better noise floor. Very subtle, extremely low-level sounds, such as the reflections from the back of the hall, were slightly easier to hear. When I compared my own DSD recordings, which could only be played on the AK120, with a 96/24 PCM conversion played on the AK100, the additional fidelity of the DSD recording came through quite clearly. The biggest difference was the added ease on the loudest passages and a less mechanical presentation overall. For those who haven't heard DSD before, listening to it through the AK120 can be a "game over" experience, since DSD successfully walks that thin line between digital hardness and analog softness.

High Points

  • The AK120 delivers class-leading sound quality.
  • The player offers support for full-resolution 44.1, as well as 88.1, 96, 176.2, and 192 kHz files. It's also the first portable player to support DSD 64x.
  • The AK120 is compatible with a wide variety of headphones and in-ear monitors.
  • The overall fit and finish is substantially better than most portable playback devices.
  • The AK120 also functions as a USB DAC.

Low Points

  • The AK120 does not come with any software for the Mac, but the Mac OS is supported for basic drag-and-drop functions.
  • The AK120 lacks a mute button.
  • The micro SD card door does not click open the way that the door on the AK100 does. It is a friction slide that often does not stay all the way open when changing cards.

Competition and Comparison
Currently the AK120 has few, if any, direct competitors. The most popular playback devices, such as the iPhone 5 and iPod Touch, do not support high-resolution files. The HiFiMan HM-801 ($749) has removable cards for storage like the AK120, but it has a maximum resolution of only 96/16 (96/24 files are down-sampled to 16 bits). The Colorfly C4 ($799) can support 192/24 files and function as an SPDIF DAC and upsampler, but its ergonomics are far more retro and idiosyncratic than the elegant-by-comparison AK120.

Obviously, not everyone needs the ultimate in sonic performance and high resolution in a portable music player. However, if you want to be able to take full-resolution and uncompressed high-resolution music wherever you go, the AK120 delivers. While its ergonomics may not be quite as slick as an Apple iPod (what is?), the Astell & Kern AK120 is easy to use, especially compared with the competition. And when it comes to pure unadulterated sound quality, the AK120 leaves every other portable player I've heard in the dust. Sure, it's expensive, especially for a portable device, but for anyone who demands the best sound quality currently available in a tiny package, the AK120 is now the ultimate device to own.

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