Well I be at work now.
I go to the sound manager, scroll down to music, and open the field I want.
Find the music I want, then right-click, and click "Use as Music"
Then I use the trigger (or used to, till i made a huge playlist)
Play Sound (First menu)
Sound - Play Music (Second menu)
Then pull down your new "Music" variable and pick it.
I did not alter any channels or property of the music variable.
* The editor has a different interface for mac? Does that mean we can only play your maps on a mac?