From my personal experience with iTunes ... it blows. I mean I downloaded this song and it has all this non-random noise in the background, which is not there in the original song. It was something like an oscillating white noise kinda sound. No it was not my speaker or my codecs, cuz all my other music (not from iTunes) played just fine. I had to fix it myself with Audacity's remove noise feature, which took a while, but worked surprisingly well. But really, they should work on improving their music quality. Maybe use flac instead of mp4 ?