Apologies if this has been discussed previously... I'm pretty settled now with AAC files at 128 kbps in my iTunes library, but started out using mp3, at varying bitrates. I now want to re-encode those mp3 files, but I'm wary of the conversion feature in iTunes. I wouldn't be too concerned going the other way, but given that AAC offers better sound quality at the same bitrate, I'm nervous that the conversion will be constrained by the original mp3 import. So, does anyone know exactly how the conversion process works? If I were to convert from mp3 to AAC at the same bitrate, will the resulting file resemble a 'true' AAC import, or am I going to have to re-import all of those CDs?