I was experimenting with 2 codecs for 6 channel audio passthrough on my apple tv 2 AAC at 768kbps 6channel passthrough vs ac3 6 channel passthrough at 600 something or other Kbps The handbrake default appletv 2 setting is track 1 AAC PLII at 160 which I bump up to 320 (the max allowed) and track 2 ac3 passthrough 6 channel at 612 or something Kbps.... I understand that AAC is a newer codec and on paper is higher quality but isn't as widely playable as ac3 hence handbrake using ac3... My Denon 1610 automatically plays the 2nd track, the 5.1 track... I ripped a couple chapters of Captain America using both codecs.... The AAC one sounded a bit brighter and like it had more transparent airy quality which then made the ac3 track sound dull.... My question is that my Denon displayed the PLII light... Is it still playing 6 discreet channels or down mixing to two channels and processing it as PLII two channels? Or is it just displaying that light for some reason and it's playing 6 discreet channels? I think a blind test would be more interesting but I'm intrigued by the results so far... I can't wait to try HD audio!