I was just messing aroud with my psp and realized that the psp can play back gaplessly using aac only. MP3 still had a small gap on the psp. I found it amazing a psp, meant for games can play gaplesly, yet the ipod can not, which is meant to play music. I just wrote to apple in their feeback page letting them know this. Any one else have an opinion on this matter? For people that want to test this, just rename your .m4a files to .mp4 files to work on psp ver 2.0 or later.