i stumbled onto something you guys might find interesting. i noticed my Windows audio panel always showed i had 7.1 speakers set up even though i usually only have a pair of headphones plugged in. this became a problem in some games like Source games or UE3-based games that set the audio based on your Windows settings. if i changed the Windows setting to headphones or stereo speakers, it wouldn't take. it would immediately go back to 7.1. i learned that if you disable "stacsv.exe" in the Task Manager you can change the settings and it will actually stick - at least until your next reboot.

if anyone has a more permanent solution, i'd love to hear it. the fix i'm using now is kind of a pain.