I have been having quite the problem hooking up my Yamaha AMP receiver to my PC. It is a 5.1 system and i know it works because when i use the FM setting all speakers and sub play. But when i try to use my PC with it i only get sound out of the front left speaker and the front right. My HD audio deck says it is using the 5.1 but when i do the test i plays front left then front right then cycles threw the rest with no sound but shows that it is using sound. I do the tone check on the Yamaha with this setting and all speakers including sub work as expected. I have tried using HDMI into the receiver as well as aux in and the basic left right with a Stereo Male To Dual RCA Female Adapter that goes into the aux in/out put green port on the computer all with the same problem