imac toslink only sending 2 channels to receiver

Hi, I have posted and looked through apples forums and have not found an answer to this. I ended up finding this site for us fellow canadians. I have both a late 2009 iMac and a 2010 macbook that I have tried to use the toslink to get 5.1 to my Harman/Kardon receiver. When I connect it I only get 2 channels of audio, no matter what Mac I have it connected too. Other devices using the same cord and setup works fine (ps3). I have tried going to the "audio midi setup" but it will still only show Stereo 2 channels, the option for 5.1 or higher is grayed out.



Can anyone help me

via ehMac.ca http://ift.tt/1cb0U0c