Audio while Alt-Tabbed

I've been looking for a way to maintain game music & sounds while alt-tabbed. While streaming on twitch.tv it is often necessary to attend to other things between rounds or at the end of a game, but it is very disruptive to the audio experience of the viewer.

I've noticed Unreal engine has a variable UnfocusedVolumeMultiplier, but I have been unable to set it in KF2. I'm thinking it's a feature request at this point :)

Cheers,
twitch.tv/Rufeooo

Audio while Alt-Tabbed