I also get this. I have a Creative X-Fi card. Stereo works fine, 7.1 works fine, but 5.1 (which is what I would like to use) has this sound. It gets worse as you move the sliders for panning and fading.
I also get this. I have a Creative X-Fi card. Stereo works fine, 7.1 works fine, but 5.1 (which is what I would like to use) has this sound. It gets worse as you move the sliders for panning and fading.