The NW-MS70D plays MP3, WMA (Windows Media Audio) and WAV files, as well as Sony's own ATRAC3 and ATRAC3plus audio files, which deliver listenable quality at bit rates as low as 48 kbps. The player comes with music-management software for creating music mixes and transferring them from your PC at super-fast speeds through a plug-and-play USB connection. A supplied USB recharging cradle connects directly to your PC.

"Easy Skip" group/folder functionality fosters easy navigation between multiple file folders transferred from original playlists. Sony's automatic volume limiter system (AVLS) conserves batteries and guards hearing by capping listening level, while a backlit LCD shows track number, bit rate, elapsed time, song title, artist name, an audio-frequency spectrum analyzer, play mode, bass setting, AVLS setting, and remaining battery life. The unit's skip-proof design uses no moving parts, so music will play smoothly right through your most energetic activities. Its embedded rechargeable Ni-MH battery provides up to 33 hours of continuous playback (when playing ATRAC3 files) and can be charged in the supplied charging stand and AC adapter.