Steven Stone is the former editor of AudiophileReview.com. 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 HomeTheaterReview.com, AudiophileReview.com, and The Absolute Sound.
Steven is plays guitar, mandolin, and Ashbory bass and is a collector of fine musical instruments.
Okay, let's give the elephant in the room a nice big comfy chair: the AK240 is the most expensive portable player/DAC made, at $2,495. It's not an "entry level" or "step up" product. No, the AK240 is aimed at hardcore enthusiasts, or "hi-fi crazies" as fellow AudiophileReview.com writer Roger Skoff likes to call the most fervent audiophiles, who simply want the best possible sound, price be damned. The AK240 is currently THE little box to incite their lust.
But perhaps you haven't heard of Astell & Kern. Three years ago, the company didn't exist. A&K is a division of iRiver, which has been making portable players since 2000. A&K's first product was the AK100 player, which shook up the portable player market with its high price ($699), stylish good looks, and high level of audio performance. The AK100 has been discontinued and supplanted by the AK100II ($899), which is now A&K's entry-level player.
The Astell & Kern AK240 is a beautiful-looking device that delivers a multiplicity of functions. First and foremost, the AK240 is a portable music player capable of playing virtually any current digital format, including PCM up to 24/192, DSD64x, and DSD128x. The AK240 supports FLAC, WAV, ALAC, AIFF, MP3, OGG, APE, AAC, DFF, and DSF music formats. It has 256 GB of internal storage and one microSD slot that can accept up to 128GB cards. The AK240 employs a 3.3-inch AMOLED WVGA (480 x 800) touchscreen display that delivers full-color graphics, as well as serving as a multi-function control surface. The AK240 has a single push button on top for wake-up and on/off, plus mini-buttons for forward, pause/play, and back on the side opposite the volume control knob.
Besides serving as a portable player, the AK240 can also function as a USB digital-to-analog converter (DAC.) As a DAC, the AK240 supports all the same bit rates and formats as when it's a player, which is pretty much everything. The only downside of the AK240's DAC functionality is that its volume control is not active when in DAC mode, so your player app or preamplifier must adjust the volume levels. The AK240 supports streaming, not only from the player to your home system via digital Bluetooth, but also from your home computer's music library to the AK240 via a WiFi connection. The AK240's WiFi connection also serves as a means for firmware updates - instead of a multi-step process using a microSD card, the AK240 can acquire the new firmware directly from the A&K site automatically via WiFi.
The heart of the AK240 is a pair of Cirrus Logic CS4398 chips, one for each of its two channels. Unlike other Astell & Kern models, the AK240 can play DSD files in their native format without converting to PCM, thanks to the addition of another XMOS processor dedicated to DSD conversion.
Astell & Kern spent a lot of design and fabrication time on the AK240's duraluminum chassis. Manufacturing it entails a 12-step process that culminates with the addition of a carbon fiber backplate. The final results are unlike anything you've seen before in terms of shape and style. Instead of another variation on the iPhone with a large front panel on a rectangular container, the AK240 has two cut corners to give it a unique shape that can be recognized even five feet away as not your typical portable player. The AK240 also comes with its own form-fitting leather case available in a plethora of designer colors.
The AK240 has only four buttons: one on top that turns the unit on and off and also activates the touchscreen, and three on the side opposite the AK240's volume control knob. The three buttons on the side control forward, back, and play/pause. There is no dedicated "mute" button on the AK240, so the small play/pause button serves as the quickest one-push way to mute the player. Otherwise, to mute the AK240's output requires you to push the on/off button, which activates the touchscreen, and then push the "pause" graphic on the screen.
The AK240 touchscreen display functions not only as a display surface that supports full-color graphics but also as a multi-function control pad. All the menus and settings are accessed through multiple touches on the screen. Given the diverse functionality of the AK240, the menus and controls are not as complicated as they might be. Some options, such as the MQS streaming, may require a trip to the AK240's owner's manual, however.
Among AK240's features is the ability to create and save different tone adjustment equalization (EQ) settings. Along with a user-adjustable 10-band EQ, A&K also includes a preset called "Pro EQ" that is a not adjustable. I tried it, and I guess I'm just an amateur who prefers non-professional EQ settings. I made and saved several EQ profiles for different headphones. Ever want your Etymotic 4P to have a soupcon more bass? With the AK240, it's a finger slide away. Unfortunately the EQ is not active on DSD files. Also the control screen is quite sensitive: adjusting your EQ on a moving train will be tricky, as it's far too easy to turn a 0.5dB adjustment into a 5dB one!
I found two ergonomic issues with the AK240. First, when I was using the AK240 as a USB DAC, if I played a DSD file on the Audirvana Plus program and then closed down the app and played a PCM file with another music player app, the AK240 would generate noise instead of music because it was stuck in DSD mode. If I went back into Audirvana and played a PCM track, all was well again. The second issue was its volume knob: if I tried to turn up the volume too quickly, it would turn the volume DOWN, not up. Only a slow steady turn ensured that the volume would go up instead of down.
You can't really look at the sound of any portable player without considering its headphone compatibility. Some headphones' characteristic impedance, sensitivity, and power requirements mate better with some players than others. I used the AK240 with a variety of earphones from sensitive in-ears like the Westone ES-5 to my least efficient and power-hungry cans, including the Audeze LCD-2 and Mr. Speakers Alpha Dogs. With sensitive in-ears, the AK240 was quiet without a trace of amplifier noise or hiss. With power-hungry earphones, I would have liked a bit more drive on some of my own DSD recordings, which because of their wider dynamic range were recorded at a lower average level than most commercial pop, rock, or jazz releases.
In terms of harmonic balance, the AK240 offers a very clean and unromantic view of your music. If you favor MP3s that have a lot of edge, you may find certain headphones, such as the Etymotic 4P, to be overly aggressive sounding without EQ. But you can "fix" some edginess by judicial use of the built-in user-adjustable EQ. In reality, there's nothing wrong with the AK240/Etymotic 4P combination that can't be solved by listening to better-quality sources. If you put garbage into the AK240, it will let you know exactly how much it stinks.
The Oppo PM-1 headphones proved to be one of the most synergistic headphone combinations with the AK240. The PM-1's high sensitivity coupled with its euphonic treble response made even ruder MP3s sound listenable. For high-resolution PCM material, I created an OPPO EQ setting that delivered an extra smidgen of high-frequency extension to increase the apparent resolution on all the High-Definition PCM music files I tried. I wish I could have used the EQ on DSD files, but as I said it is disabled when playing DSD. Perhaps the next firmware update will include this feature.
Click over to Page Two for High Points, Low Points, Comparison & Competition, and Conclusion...
• The AK240 is beautifully made with a stylish design.
• The AK240 supports every current consumer format.
• The Astell & Kern AK240 offers superlative sound.
• There's no built-in volume control when used as a USB DAC.
• The volume control knob can be difficult to turn up quickly.
• With the Audirvana Plus playback app, the AK240 can get stuck in DSD mode.
Comparison and Competition
I had five other portable players in-house during the review period for comparison: a 160GB iPod classic, an iPhone, an Astell & Kern AK100, a Colorfly C4, and a Calyx M player. For sound quality, the Apple iPod 160 was not competitive with any of the other players. The AK100 and Colorfly C4 were closer but still not quite equal to the sound quality of the AK240. Only the Calyx M matched the AK240's sonics. Also, all of the other players lacked the plethora of features found in the AK240.
The Astell & Kern AK100 has been solid and completely glitch-free during the year I've had it. It is as quiet and noise-free as the AK240 with sensitive in-ear monitors, such as the Westone ES-5. The AK100 also drives high-impedance, low-sensitivity earphones, such as the Beyer Dynamic DT-990 600-ohm version, almost as well as the AK240, but it did need somewhat higher volume settings to achieve the same levels, so the AK100 ran out of gain before the AK240.
The Colorfly C4, while limited in that it can't play any DSD files, does have a powerful headphone amplifier that was silent with high-sensitivity in-ears while having just enough juice to drive the Audeze LCD-2 bamboo headphones. On my own hi-res 24/192 recordings, the Colorfly had barely enough output level to play loudly with the Audeze, however. Sonically the differences between the AK240 and the Colorfly on 44.1/16 Redbook files were minor. The AK240 had a slightly more linear harmonic presentation, while the Colorfly has a bit of additive harmonic warmth compared with the AK240.
The Calyx M ($999) proved to be the most sonically competitive with the AK240. Both produced excellent sound on anything I threw at them. The Calyx doesn't have all the capabilities of the AK240; it's "only" a portable player and a USB DAC, and the internal storage is just 60 GB, but it has a very refined interface and ergonomics. Although blessedly silent with sensitive in-ears, the Calyx M had barely enough gain on my own hi-res recordings; I had to push the sliding side-mounted volume control all the way up to max, unlike the AK240.
The Astell & Kern AK240 is, quite simply, the best sounding, most fully featured, and most stylish portable player currently available. If you want a portable player that can serve as a streaming client, as well as streaming source, play 128X DSD natively, and receive firmware updates wirelessly, the AK240 is the only player that can do all this. Whether it's "worth the money" depends more on your own relationship with money than with the AK240's price. If you want "the best" portable player right now, the AK240 is the only game in town.
• Astell & Kern AK100 Portable Music Player Reviewed at HomeTheaterReview.com.
• Astell & Kern AK120 Portable Music Player Reviewed at HomeTheaterReview.com.
• Visit the Astell & Kern brand page at HomeTheaterReview.com.