The AK Jr is the first Astell & Kern music player I've reviewed, and it's a doozy. There's an undeniable elegance to the look and feel of the AK Jr you won't find in FiiO, Pono or Sony players. The AK Jr is company's least expensive player -- it was $499, £399 or AU$699 in Australia, but now it's $299 in the US, £249 or AU$499!
A sleek, slim machine, its aluminum body measures a trim 4.6 by 2.2 by 0.35 inches (117 by 56 by 8.9mm), and its 3.1-inch (79mm) LCD touchscreen dominates the front panel. There's 64GB of on-board memory, and Astell & Kern claims the AK Jr will accept microSD cards up to 200GB.
Resolution tops out at 192 kHz/24 bit, and AK Jr plays MP3, FLAC, WAV, ALAC and DSD files, although it converts DSD files to PCM digital for playback. Connectivity is limited to a 3.5mm headphone/line output jack, a Micro-USB port and Bluetooth for wireless fans. Maximum play time is 9 hours. Astell & Kern offers optional slip-on cases in a variety of colors.
Navigating menus on the touchscreen wasn't as intuitive as I would have liked. I find the newFiiO X5 second-gen player's user interface easier to fathom.
It may seem like a small thing, but I really like the volume control knob that's tucked into the right side of the player. Most portable music players make do with volume +/- buttons to adjust level. With the AK Jr's knob it's easier and faster to zero in on exactly the volume you want.
As for its sound quality, starting with my Oppo PM-3 full-size headphones , it was first-rate. There's clarity coupled with impressive dynamic contrast that I never heard from a FiiO player, including the new X5 second-gen player. Bass definition is superior -- the AK Jr's control on my Aphex Twin electronica albums trumped the X5's bottom-end. The difference between well-recorded standard and high-res files was easier to appreciate over AK Jr.
Next, I spent some time with my Grado SR325e headphones plugged in. Pairing success was a little less clear-cut, the AK Jr's transparency was there for sure, but the bass was a tad lean. The X5 second-gen player's richer balance warmed up the SR325e sound, while forfeiting some detail and air.
Then I made time for the Ultimate Ears 900S in-ear headphones, and they told the same story, the AK Jr sounded powerful, open and clear.
You can also use the AK Jr as a USB digital converter/headphone amp with your computer or laptop. I'm not sure why, but my files sounded more transparent and clearer played directly from the AK Jr than from iTunes on my Mac Mini computer through the player.
After the original review posted in 2015 I listened to the Audeze Sine on-ear headphones with the AK Jr, and found them a truly synergistic match. The Sine's bass was abundant and taut, and their lively dynamics and clear treble were given their full due with the AK Jr.
Editors' note: This post originally appeared on July 11, 2015, but has been updated with new pricing.