when you say "from a hard drive using channel A"
I am a little confused... maybe you mean from the built in player in Master Fader...
Or do you mean you have music on a USB jump drive?
I normally use break music from "Airplay" which is a feature of the Apple Airport Express router.
This router has a 3.5 mm stereo headphone jack that is connected to a couple of inputs on my DL32R.
Conveniently, the iPad's "Airplay" feature is set to stream it's iTunes music "wirelessly" to the Apple Express,
so when the band goes on break it is a simple tap of the "BREAK MUTE"
Music plays, and the lead vocal's mic is left on in case announcements need to be made and I am getting a Pepsi from the open bar and not being attentive.
Is that more confusing ...