Depends on what you are using to play the music.

CD music is recorded at 128kb/s 44hz stereo (2 channel)

Use of higher bitrates than this in mp3's etc etc is an attempt to compensate for the lossy compression format, and it works to some extent, the arguements being generally at what level it no longer adds any value.

DVD music or Digital TV (SD) is usually 192 to 384kb/s 48hz, It may be 2 channel through to whatever the latest and greatest surround sound format is. There are several formats the sound can be in Mpeg2 and AC3 being the most common.

So if you are playing the music back over a DVD home theatre system, 5.1 or 6.1 sound, it may be more of interest to you to look for Video clips of the music you want, in original format (720 x 576 mpeg2 or whatever x 480 if you live in NTSC land), at around 300meg a pop. Then with the better quality sound, you also get the film clip as a bonus. You might get the video clip reduced to 320 x 240 2 channel sound for around a 60 meg download, but the sound is unlikely to be anything but 2 channel.