Review: Astell&Kern AK100 Portable Music Player

First, the obvious: The Astell&Kern AK100 is beautiful, both visually and in tactile terms, much the same way as the first iPod you ever saw was. Who cares what it is or what it does? You just want to hold it. And own it.

Some backstory. Astell&Kern is a new upscale brand from iRiver, one of the very few MP3-portable makers surviving from the pre-iPod/iPhone age. (Remember the Rio? That was theirs, too.) The AK100 is iRiver’s marquee product (the Astell&Kern moniker’s origins are obscure, at least to me), a pocket-size solid-state player that can reproduce both standard MP3 files and high-rez audio in formats including FLAC, Ogg, WAV, and WMA, carrying up to 192-kHz/24-bit resolutions, through legitimately high-end digital-to-analog and headphone-amplification electronics.

However, the AK100’s original firmware did not allow it to play AAC (Apple Audio Codec/MP4) files. Fortunately, an update arrived during my review period that added AAC, ALAC, and AIFF support. 

In terms of sound quality, the AK100 is without peer among portables. Load a great lossless, high-rez recording and jack in a great pair of cans, and the MK100 will instantly remind you why serious headphone listening is so compelling.

The quality of the A&K’s electronics, which include a Wolfson 192/24 digital-analog converter and a demonstrably better-grade headphone amplifier, is obvious: Dynamic peaks sound airy and effortless. Just as tellingly, I could hear the noise floor on a few 24-bit recordings, which in practical terms is around 10 dB below that of CD-standard digital audio, making this an impressively wide-dynamic-range listening system.

Few recordings could better demonstrate all this than Dr. Chesky’s Sensational…Binaural Sound Show, a demo grab bag of headphone-optimized material downloadable from (It’s also available on SACD and CD.) A brief trap-drum solo gave an electrifying taste of the dynamic integrity the A&K could deliver while reminding me what cymbals actually sound like in real-life acoustic spaces. A Mozart chorale for small choir and organ, recorded in New York City’s long-reverb Church of St. Paul the Apostle, sounded unreal. From the first D1 pedal of the organ (around 36 Hz — I don’t think I’ve ever heard anything that low from my iPod!) to the last grainlessly fading echo, the sound was simply glorious.

The A&K played amply loudly through 3 different sets of ’phones I tried. These included 70-ohm Sennheiser and Sony, and 15-ohm Etymotic models. At full output the first two were quite loud but not painfully or — perhaps — dangerously so, while the in-ear Etys were uncomfortably loud.

Ergonomically, the AK100 is no iPod. Don’t misconstrue that: It’s eminently usable, but it also harks back to the pre-iPod era. Once you’ve USB’d it to your PC or Mac, it appears as just another data-storage “volume.” There’s no using iTunes or otherwise auto-synching; file-loading is strictly a drag-and-drop, folder-based affair, though the PC-only iRiver Plus 4 “music manager” application supplied with the AK100 bridges the gap a bit. (A&K’s literature lists only Windows as a “compatible operating system,” but I had no trouble mounting the AK100 or managing its contents with my iMac.)

There’s a very basic in-player playlist-making routine, and similarly unfancy album/artist/song search facilities, but certainly no “Genius” (or even Dopey) to do the heavy listing for you, and swiping around the AK100’s folder/album structure is, comparatively speaking, a bit clunky. With 32 GB of onboard memory and 2 Micro SD slots, the AK100 can pack up to 96 GB, though the track-count capacity will be much lower if you load many high-rez files, which are at least 10 times as bits-hungry as typical MP3s.

In everyday ops I found the AK100 to be smooth and pleasant but — again — no iPod. The mostly intuitive touchscreen interface presented me with little difficulty in figuring out its organization or operation without reference to the online manual. Its swipe-and-tap responsiveness is perfectly decent, but there’s a half-second or so delay interposed between touch and response. Worse, it takes almost a full 30 seconds for the player to power on and be ready to play — eons, in Apple years. A “sleep” mode helps, but it’s less power-conserving. (iRiver rates playback time as “up to 16 hours.”)

I loved having a physical volume knob (you just can’t beat ’em for ease of use), but the A&K’s sticks out in a way that seems doomed to eventual breakage. And it rattles, softly but annoyingly, when you touch it or move the player around briskly — totally out of character for otherwise so classy and billet-like a device. A trio of play/pause/skip hardware keys along the left-hand edge functions in the usual fashion.

The AK100 incorporates Bluetooth to link wirelessly to BT headphones, or to certain A/V receivers and the many BT-equipped all-in-one/portable speakers . It’s kind of a mid-fi feature on so high-fidelity a device, but it should work adequately if you’ve got to have wireless. (At the time of this review, I lacked a Bluetooth receiver with which to try it.) The AK100 also has a “Toslink mini” optical in/out, allowing it to both function as an outboard DAC and send its bitstream to another system.

Reading all this over, I note a lot of comparisons and complaints. But if you indulge yourself in one 2-minute listen, you’ll ask, as I do, “Who cares about all these stupid niggles?”

Or even about the price. The AK100 sounds so good that it shows us what portable music could be, and should be. And, from Astell&Kern at least, what portable music is.