Hi Shaun! Its AAC and yet another encoder technol. in the world to make your audio files smaller, while still sounding as it should. This one has nothing to do with how multichannel audio is processed in DVD streams. Head over to www.apple.com and go to the i-tunes tab to find out more on apple's contribution to lossless audio compression, if you are interested. I don't know the details, I just discovered that when using AAC in i-Tunes I wasn't missing as much of the sound as when using MP3 even in highest quality setting. But then again its all based on perception and dus deception of the brain. ----- Original Message ----- From: Shaun Turner To: The moon: beautiful. The sun: even more beautiful. Sent: Thursday, May 20, 2004 2:52 PM Subject: RE: [Yello] Winamp or i-Tunes i thought acc was one of the surround sound formats on dvd's and the like? that allows for 5 channels (or more probably) whereas your standard mp3 format is a single stere channel i'm probably wrong tho shaun