The chapter on the Wavelet transform in "Numerical recipes" is quite a good introduction.
PCM audio generally compresses poorly using run of the mill Huffman or LZ schemes, but you can get 2:1 or so using audio specific data compression routines, I doubt that the sandforce part will implement these.
Besides a disk controller that advertises numbers assuming compressible data is cheating in my view.
No DAW will be compressing its internal data, it is too computationally expensive, but storing sample libs lossless compressed is reasonable (Decompression is typically **MUCH** cheaper then compression, and some of those datasets are huge).
Audiophiles use phono leads because they are unbalanced people!