My iTunes library is starting to approach 20 gb with about 95 songs encoded in mp3 at 192 kbps. I would like to encode them to aac at 128 or 160 but I've heard you shouldn't convert mp3 to aac. Would there be a great loss in quality if I was to do so? I'm not looking for the songs to be perfect but pretty good quality. Thanks for any advice Edit: I meant to say 95 percent of the songs not 95. I don't think 95 songs would be worth to reencode to aac.