I've tried a whole bunch of things, but it was like a year ago so I don't remember exactly what I did. I'm pretty sure I don't have a 'stereo out' option, only line-in and microphone. My old PC had it, but my new one doesn't. I should go try in Linux, to see if it's a hardware issue or a driver issue.
Unfortunately, I can't check right now because my graphics card is dead and I'm waiting on a replacement.