Im trying to get the SPDIF digital coax jack on my gigabyte K8NPro to work properly. When I connect it to my sony 5.1 system I only get two channel sound. The only setting I can find is the speaker setting under sound and audio properties. When i change that to 5.1 speakers I still only get the same result. Is there some other setting I need to change. I know it has nothing to do with the reciever as its set up and working properly. Any helps appreciated.