This is very interesting, and might explain similar issues other users reported.
I think it's a bit of a problem because, most games out there that use positional 3D sound, like GSX, will surely use mono Waves, since you cannot place a Stereo sound in the 3d space.
But it must be related to the audio drivers and audio hardware used, because I still can hear mono sounds just fine. I have two audio devices, the normal speakers and a USB headphone, and they are both working normally.