I'm trying to decide if I should convert my entire iTunes library from MP3 (@320kbps) to AAC (@320kbps). There's two motivations for this: - Better sound quality - Less HDD space AAC is supposed to be better for sound quality, but is that true when you convert from an existing MP3 file, keeping the same bitrate? I'm worried that converting one compressed file format to another might further degrade the original "copy", and therefore the overall sound quality. Can someone please clarify? Also, assuming I have about 30GB of music in MP3 format, how much space can I reasonably expect to save if I convert all of it to AAC? Again, I would keep the same 320kbps bitrate. I have an iPhone, iPod, and iPad, so compatibility isn't an issue. I'm only concerned with (1) audio quality, and (2) space requirements. Thanks!