The Cowon iAudio M5 sounds very good, but right off the bat, you'll want to upgrade to better headphones. Although its included earbuds perform better than some we've heard, they were easily trumped by a $5 set of Coby 'phones. To test the M5's musical wherewithal, we donned a full-size set of AKG K100s and fired up some high-bit-rate audio files, as well as noncompressed WMAs. Music consistently sounded clear and vivid in the treble frequencies, midrange sounds were as natural as we've heard with any portable player, and ample bass was on hand, thanks to the adjustable bass-boost feature. The iAudio M5's 20mW-per-channel amp proved capable of playing adequately loud with the multiple sets of headphones we used in testing. The player's built-in mic effectively picked up voice recordings, which also sounded clear in part because we took advantage of the 128kbps-bit-rate recording option. On one occasion, the player froze, but we can't hold that against the M5 because it happened shortly after we tried to play a DRM-protected WMA file, which the player doesn't support. More disturbing, however, was that after just a few days of using the player, the right channel began to short out whenever the headphone plug was jostled a certain way, regardless of which headphones we used with the player.
Transfer time to the Cowon iAudio M5 over USB 2.0 was an exceptionally speedy 7.25MB per second. Cowon's marketing materials claim the lithium-ion battery delivers 14 hours of playback. In testing, we got approximately 15 hours of playback from a full charge, which is about average in comparison with comparable players. If you're looking for longer battery life, consider the iAudio M5L players in the series.
In the final analysis, more up-to-date features, such as support for protected WMA files and ID3 tag-based music navigation, would make the Cowon iAudio M5 a serious contender among hard drive-based portable audio players.