Sound in background?

[SloppyBeaver]

I use multiple monitors and I switch all the time in Maximized Windowed Mode. Is there a way to set up Sound in Background so I don't keep cutting out the sound when i change screens? For example im on my right monitor typing this post while main screen has wow on it muted.

[Snow240]

I would also be interested in this. It appears to have not been added in-game until TBC.