Audio Streams

Do you travel? Commute, perhaps? Just like to listen to music privately around the house? No matter—the Astell&Kern AK240 is the luxury choice in high-resolution portable music players (footnote 1). It even comes with a lovely leather case that beautifully cradles its angular beauty. The AK240 can play all of your PCM files, up to a resolution of 24-bit/192kHz, as well as DXD and single- and double-rate DSD, natively, and can do so from its internal storage, from a microSD card, or from your computer via WiFi or a wired connection. It can also function as a DAC or USB-to-TosLink converter. I'm not so sure there's much left wanting.

The Astell&Kern AK240
The Astell&Kern AK240 ($2500) is milled from a solid billet of aircraft-grade duralumin, and each player undergoes a 12-step process for the gunmetal-finished casework alone. Drilled and filled, the AK240—roughly the size of a deck of cards—houses dual Cirrus Logic CS4398 DAC chips and, through a top-mounted, 2.5mm tip-ring-ring-sleeve (TRRS) jack, offers a true balanced headphone output. Next door to that is a regular 3.5mm jack that can be used three ways: as a single-ended headphone jack, a TosLink digital output, and line-level out. The headphone outputs are specified as having a 1 ohm impedance, with a maximum level of 2.1V RMS (unbalanced) and 2.3V RMS (balanced). Finishing off the top edge is a press-and-hold on/off switch that, with a shorter press, also turns off the AK240's touchscreen.

The AK240 supports these file formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, and DSF. If you connect your computer to the Micro USB input on the AK240's bottom, the player will charge while also functioning as a PCM/DSD DAC, so you can send your computer-based tunes through it to your headphones or hi-fi. You can also play music from the AK240's 256GB of internal memory, and expand that memory by another 128GB through the use of a microSD card. Three buttons on the left side allow for basic playback functions, including Play/Pause, Next/Fast Forward, and Back/Rewind. These buttons worked flawlessly, even through the dark olive-drab leather cover. The microSD card slot sits below these buttons.

Most of the front of the AK240 is taken up by a 3.31" AMOLED WVGA (480x800) touchscreen that acts as your window onto all of the AK240's functions. A knurled volume knob sticks out from the unit's right side, protected on two sides by the duralumin body—but you can also adjust the volume from the touchscreen. Astell&Kern claims that the AK240's 3250mAh 3.7V Li-Polymer battery takes about four hours to fully charge from empty, after which it's good for about 10 hours of play. The rear surface hasn't been neglected, even though there's nothing on it except the Astell&Kern logo, floating over a lovely carbon-fiber skin.

The multipurpose AK240 can stream music from any Windows or Apple computer via WiFi, through Astell&Kern's MQS app. Just download and install the app in your computer, connect the AK240 to your WiFi network (802.11 b/g/n), and select MQS from its home screen. After the app automatically finds and displays your MQS-endowed computer, you can then browse its contents and any attached storage by Songs, Albums, Artists, Genres, or Folders. To view the contents of the AK240's internal storage and microSD card, just go to its home screen, there's a handy button just for that purpose on the bottom of the AMOLED screen, and select Songs, Albums, Artists, Genres, Playlist, or Folder.

You can load files into the AK240's internal storage when the player is connected to your computer via USB simply by dragging and dropping music into its Music folder using iRiver's free Android File Transfer app. Or, when playing music in MQS mode from your computer, you can tap on an album or song, then select Download, which will copy the selection to the AK240's internal storage. However, if you're listening to music while downloading in this manner, you may experience dropouts, as I did. And as long as your computer has a microSD slot, you can fill the AK240's card with music simply by inserting the card into it and dragging and dropping.

The AK240 will let you know when an update of its firmware is available, which you can then install via WiFi. I recommend considering these updates mandatory; they can include performance enhancements as well as bug fixes.

The MQS App
Using the AK240 to play music is, thankfully, a simple and relatively intuitive experience. That said, just how intuitive you'll find it will depend on your comfort level and familiarity with app-based playback. I'm certain my teenage daughters would find using the AK240's interface second nature. Navigation is simply a matter of tapping on your selection on the touchscreen. When you browse to Album view, you tap to view the contents of an album, or tap and hold the album cover to play the entire thing. You can also create and save playlists, or just play music as you go. If you want to add another selection after the music you're listening to ends, tap on it and select "Add in Order" or "Add After Playing."

Using the Settings option from the home screen, you can access such features as WiFi, Bluetooth, Equalizer, Gapless playback, Line Out, Balanced out, LR Balance, Brightness, Theme (this changes the look of the player's touchscreen), Date and Time, Language, Power, USB Connection (MQS or DAC mode), Downloads, Update, System Info, and Default Settings. Swiping in a downward motion from the very top of the screen reveals many of these same settings options. Tap and hold to enter each options setup mode, where available.

You can also search the contents of the AK240's internal storage. Search results begin to appear as you type. Overall, I found the MQS app a breeze to use, though having grown accustomed to using an Apple iPad as a remote control has made smaller screens feel, well, smaller. I imagine that people with big fingers would have a tough time making some selections on a 3" screen.

The AK240 as Portable Player
I mainly paired the Astell&Kern AK240 with NAD's Viso HP50 headphones, which present a relatively easy load. This combo delivered clean, clear, very resolute sound with nicely defined edges, well-controlled yet ample bass, and a nicely colored midrange. I sampled all manner of music files, including CD-quality and higher-rez PCM up to 24/192, as well as DSD, and the AK240 mainly performed without a hitch (see "Niggles," below). This included playing from internal storage, from the microSD card, via MQS WiFi, and wired streaming from my iMac and mounted Network Attached Storage (NAS).

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Footnote 1: Astell&Kern, South Korea. Web: www.iriver.co.kr. US distributor: iriver Inc., 39 Peters Canyon Road, Irvine, CA 92606. Tel: (949) 336-4540. Fax: (949) 336-4536. Web: www.astellnkern.com. John Atkinson reviewed Astell&Kern's entry-level AK100 portable player in August 2013.