WavPack allows you to losslessly compress (and restore) both 16 and 24-bit audio files in the .WAV format. Unlike “lossy” compression schemes (like MP3) that discard information, WavPack converts the audio data into a more compact form so that the restored files are digitally identical to the original source. It’s somewhat like the file compression portion of WinZIP except that it’s optimized for audio data. Like other lossless compression schemes the data reduction varies with the source, but it is generally between 25% and 50% for typical popular music and somewhat better than that for classical music and other sources with greater dynamic range.

http://www.wavpack.com/