I realised last night that I was only sometimes getting audio from my center speaker using the spdif out to external receiver from my Shuttle onboard nforce2 audio. There is lots of discussion about this known problem over on nforcers hq. I am going to do a clean install tonight as I have installed and uninstalled so many drivers I have forgotten where I am at. I did manage to get it fixed, but now the system is running sluggishly, so have probably broken something else in the process. When the center speaker is not working, the front left and right create the channel, obviously I don't want that, I want the 5.1 streams sent through to the amp as they are. Anyone know of the definitive fix? The fix I eventually found was a mixture of enabling hidden settings in nvmixer, and a regsitry edit.