I have a late 2011 Powerbook Pro which should allow one to connect to the tv using an HDMI cable after using a Thunderbolt output from the computer to an HDMI cable into the TV. The picture was perfect but no sound. The reason is there are no speakers with th plasma tv. I run my sound through an Onyo DS 989. So I got an optical link (MINI) to Toslink and plugged it in to my third optical input on the a/v receiver- SILENCE. Then I switched it to the 2nd optical input by first removing theDVD input. Voila it worked so the issue is with the third jack. What do I need to do to either activate the Third Optical?