I recently set up a surround sound system at home, and I've noticed something. Typically, when I'm playing former MP3s through iTunes on my MBP (connected to my AV Receiver through a digital optical cable) it plays only in stereo. However my iTunes downloads play in full surround sound. How come? I was under the impression that while AACs are capable of surround sound typically iTunes downloads are in stereo. Am I wrong? Also, is there any way I can get my former MP3s now converted to iTunes format to play in surround?