Hi, I have noticed that when only 2 speakers are being used sounds that would come through the center speaker of a 5.1 setup are missing (or possibly just too quiet), rather than being properly mixed into the left and right channels. This is really obvious by playing GTA:vice city (engine noise in a car is far too quiet). Also the music in the Halo demo is missing with HW acceleration on. I am unable to test with a 5.1 system so I don't know if it works properly there. I am using a Soudblaster Live value and the 3535 drivers by the way.