Stereo Mix in Bootcamp not appearing...

Hi!

I'm trying to stream gaming and such, but to do so I need Stereo Mix on my Windows 7 partition for the sound of the game to come through on xSplit.

I've tried the usual, 'right click in sound options > show disabled options', which is the go-to for enabling Stereo Mix on Windows 7 normally, but even doing that, it doesn't appear. I also tried downloading VAC, which didn't work. I've also updated all the bootcamp drivers, as well as the sound card drivers.

Google hasn't been any more help other than what I listed. :/

I'm using a mid-2010 iMac. Thanks!