FiiO doesn't have drivers for the E10K. I've been using the ones that come with Windows 10. And those drivers were reinstalled when I reinstalled Windows 10.

And yes, I did make sure to disable sources of sound that I wasn't using, leaving my E10K as the only source of sound in the Playback Devices.

I feel bad that I just paid for a month of game time but I can't really play the game. Do you know if there's anyway to get a refund or to save my game time for a later date when I don't have this problem anymore?