Is the mini optical output jack on the MBP only able to send two channel audio? My home theatre receiver is set to the exact same settings as my PS3 and my PS3 sends 5.1 surround no problem. My PS3 uses HDMI to connect from the PS3 to the amplifier, and then another hdmi cable to go from the amplifier to the tv. When I hook up HDMI and from my MBP my receiver will not detect full surround, it only uses two channels. The video is fine. (however the resolution is not that of my native tv resolution, but that is less of a problem now) In the Audio-MIDI utility I can change the output option from 2 channel to encoded digital but with that option I get no sound at all anymore. If I go into configure speakers with either the 2-channel or encoded digital audio selected I can open the drop down menu where it says stereo and see 5.1 surround etc. but cannot select them ... they are greyed out. I have verified that my receiver correctly uses as many channels as the inputting device allows. My Ps3 is setup exactly the same way and my receiver automatically detects 5.1 surround and uses it but my receiver only recognizes 2 channel from my MBP. Why can't I select 5.1 surround in the audio-midi setup? And the source, is a 5.1 out video file, that I am attempting to connect to my amplifier. I have the onkyo 805 amplifier. Please help. Thanks.