HI Barry,
If you don't want to degrade the sound, then you need a lossless compression format. I use FLAC (Free Lossless Audio Codec). It usually compresses the matieral quite well, on average to about 40% of the size, but with no loss (i Can recreate the .wav file if I want to). A lossy scheme like MP3 cannot allow one to recreate the .wav file if one wants to.
Hope this helps.
-akhilesh