I have a MBP from Feb 2008. I used to be able to use an optical cable sending audio to my Bose home theater receiver. It's been a long time however since I've tried to do this, as I was using an Apple Tv for a while, but now I'm all into Plex. I went to use my optical out on my mac, and it's not working at all. I remember a while ago I think I tried to use it and it didn't work as well, but this was a few months ago. I bought a new one, but still nothing. I don't see any kind of light coming out of the end of either cable I have. I have Perian installed, - I set it to multichannel output. In the sounds option, I've made sure to have Digital Out selected. In the audio midi control panel I have: Built in Output settings - Source: Digital out 48000khz ...default output and system output are set for built in output. I remember a while back, when i was trying to ac3 passthrough to work with quicktime, I followed some guide to change a setting... but I don't remember where or what it was. Thanks for any help or suggestions.