Astell&Kern, a subsidiary of the Korean company iRiver, has unveiled its AK120 high-definition mobile music player. The $1,300 AK120 is capable of playing 24-bit, 192-kHz music files—the highest-resolution files commercially available. These high-resolution music files can be purchased through such online retailers as HDtracks (www.hdtracks.com). With dual single-channel digital-to-analog converters and the ability to store as much as 192 gigabytes of music, the easy-to-use touchscreen AK120 provides an au…