I usually do one file per CD. You can usually just cat .mp3 files together, although some apps that expect non-standard metadata can get confused (mp3wrap is a more robust solution). 'cat *.mp3 > disk.mp3' (assuming that ls order is the order you want. Or 'cat first.mp3 second.mp3 last.mp3 > all.mp3') Other formats (like m4a) can be stitched together using utilities like ffmpeg.