Korean firm Astell&Kern began its involvement with high-end audio by manufacturing advanced portable music players, from its $499 AK Jr through the premium AK380. Capable of playing native DSD and carrying a $3495 price, the latter is reportedly a spectacular implementation of a portable music player.
Having already established a line of portable players, it was natural for Astell&Kern to bring its technology to a home system. The result is the AK500N network player, a product whose strikingly original industrial design is as innovative as the product itself. The casework is milled from thick aluminum plates, machined smooth and anodized black or silver. The AK500N looks like an aluminum cube with a faceted front panel, which measures 8.4" x 9.6" x 9.4". (OK, that’s not quite a cube, but it’s cube-ish.) The main body of the AK500N is supported by an aluminum plinth with four feet.
A 7" touchscreen LCD panel folds flat on top of the chassis—it’s like having a small tablet computer built into the player. When the touchscreen is raised and positioned vertically, the total height of the unit is about 14½". The touchscreen provides all the controls necessary. Although not really large, the AK500N looks very solid, and at a hefty 25.1 pounds it definitely is solid. And the price tag is equally hefty: $12,000. Due to its dimensions, the AK500N won’t fit on most hi-fi equipment racks; it’s essentially a top-shelf unit—in more ways than one. And what’s that “MQS” thing in the title? Have we added yet another acronym to our lexicon? Well, it seems that Astell&Kern uses MQS to mean Mastering Quality Sound, its term for high-resolution audio. OK, now you know.
Unlike many servers, the AK500N includes an internal DAC. It also provides lots of digital outputs, so you can use an external DAC of your choice, which strikes me as a wise fail-safe provision; no matter how good the internal chip is, there’s bound to be a better one eventually, and considering how fast DAC development is progressing, it may not be too long before a better one is available. Inside the AK500N, two Cirrus Logic CS4398 DAC chips take care of the digital decoding chore. Music file storage is handled internally by solid-state drives (SSD), with up to four drive bays available. The review unit had a single 1TB SSD. Why use expensive SSDs instead of much cheaper hard drives? According to Astell&Kern, the SSD is about five times faster than a hard disk drive, is much more durable, and is silent in operation. I think they also have lower jitter than hard drives. In addition to the SSD storage, the AK500N lives up to its network-audio-player designation by playing files from a NAS drive, which can be as large as your budget permits. You can either plug in an Ethernet cable to attach the unit to your network, or using the small antenna on its back, connect to the network wirelessly, like the Auralic Aries (to which I compare the AK500N later in this review). It can also play files from attached USB drives, either external hard drives or flash drives, and from a microSD memory card—all in all, amazing versatility!
The AK500N plays a variety of music file formats: PCM encoded files include WAV, FLAC, WMA, MP3, OGG, APE (Normal, High, Fast), AAC, ALAC, and AIFF with sampling rates up to 384kHz (DXD) and DSD files including DFF and DSF up to DSD128 sampling rate. DSD files can be played without conversion via DSD over PCM (DoP) encoding. In practice, the AK500N has a software switch to convert PCM files to DSD64 files and play everything back as DSD files. Apparently there was a demand for this feature from the Astell&Kern portable player owners. If PCM au naturel is OK with you, this option is defeatable.
The AK500N uses a battery power supply that provides around seven hours of playback time—long enough for any of my listening sessions. The supply uses a replaceable 10,400mAh/7.4-volt lithium-ion battery. The battery charges automatically when its capacity drops to four percent, or when it’s not playing. An in-line switch mode power supply recharges the battery, which takes about three hours. If the battery is depleted, the power supply, which is very quiet, will run the unit. The AK500N ships with four different power cables, with plugs for different parts of the world, and comes with a stern warning not to use other power cords. Since the battery power supply runs the AK500N, and the power cord only feeds the recharger, it should be OK to skip using a fancy audiophile power cable. Two of the cords look identical, but one has a tag identifying it as usable in U.S. territories.
A feature I appreciate in servers is an internal optical drive that can rip CDs to files on the internal storage. The AK500N’s optical drive rips to either WAV or FLAC formats. Ripping is a one-click operation, with metadata cover art provided from the Gracenote online database. Remember, the WAV format stores very little metadata and takes up nearly twice as much storage space as the FLAC format. However, some folks think it sounds better. The optical drive is accessible through a slot centered on the front panel near the top.
The AK500N can be used to drive power amplifiers through its two variable analog ports, one balanced, one unbalanced. Only one port at a time can be used. Besides the variable analog output, there are two fixed analog ports, which bypass the variable ports. You’d use the fixed ports when you connect the AK500N to a preamplifier or an integrated amplifier—something with its own volume control. There’s no analog input, so you can’t connect a tuner, phonostage, or other analog source. Still, if the AK500 is your only program source—which will probably be the case for a lot of listeners—you can skip a preamplifier in your system and use the AK500N to drive a power amp directly. Astell&Kern has in the works a matching power amplifier that would be just the ticket to use with the AK500N. A large knob, referred to as the Volume Wheel, on the right side of the AK500N lets you control the volume. What about the remote control? One of those is not provided, although the app that offers these functions became available just as this was going to press. There is, however, a very functional substitute from another company, as described later.
There are three headphone jacks on the right lower side toward the rear of the AK500N, one 2.5mm, one 1/4" and one 3/8". The 2.5mm jack supports four-conductor balanced headphone plugs. While I appreciate having headphone jacks in a server or DAC, the placement on the AK500N could be more convenient—for instance, on or near the front. But this is a minor quibble. A small button on the right lower side of the AK500N towards the front is the power on/off switch. Because it’s easy to reach from the front, the power switch is convenient. A discreet white LED on the front of the unit shows when the power is on or off. There’s also a small opening just in front of the headphone jacks into which you can plug a microSD card, the type used in camera memories. You can play music files stored on the microSD. Note that this is not the full-sized SD card, but the very small microSD card.
The warranty on the AK500N is one year parts and labor. To me, that seems rather meager for a $12,000 unit.