The quality of the Apple Lossless codec is equal to that of the CD that you put in your Mac, with no degredation of quality... which is bette than all versions of mp3. I believe that in kbps terms, cd-quality is 1411kbps, and apple lossless would be equal in quality, but less kbps, more like 700, whereas 320kbps mp3 would be less quality than apple lossless. Whether it's a noticeable difference would probably depend on your ears and your stereo setup, but there is a difference.