I recently imported a batch of CDs through iTunes 6 and 6.01, using the AAC encoder at 192 kbps. I've since noticed that some of the tracks are distorting slightly during playback. I thought it might have been my speakers at first, but I ran a few tests, and the problem appears to be the AAC encoder. The distortion isn't evident on the original AIFF file, nor on MP3 files encoded at various bit rates. It isn't a bit rate issue either: the distortion is evident at all AAC settings from 128 to 320 kbps. Has anybody else experienced this problem? This hasn't been an issue with previous versions of iTunes, so I'd like to revert to version 5 and see whether that makes a difference. I trashed iTunes 6.01 and associated plists, but iTunes 5 refused to install. I assume there's a trick to this; can anybody let me know how it's done? Update: I managed to find and trash all of the iTunes files that were preventing the installation of an earlier version. Disappointingly, the distortion is present in versions 4 and 5 as well. Could this be a problem with my optical drive?