I've built a HTPC with a Chaintech AV-710. The receiver is a Sunfire Ultimate Receiver and I'm using the optical in. Using the 5.1 speaker tests from Microsoft I'm only getting 2-channel stereo outputted to the receiver. Doing a little seaching here, it looks like that's all I'm suppose to get. I'd really love to get 5.1 from "Step Into Liquid" or "T2: Extreme". Is this possible using the digital out?