I currently have quite a few (~4500) songs in mp3 format in my Itunes of varying bitrates. I was wondering if it would be worth it to convert all of music to 256kbps AAC, will I notice any quality differences?? Can a song sound better after it has been compressed down to 128k MP3 then uncompressed slightly to 256 kbps?? Or would I be wasting my time?? Thanks for any advice, this is my first post on MacRumors.