Hi wynnd
I know there is a solution for every problem, but from solo act to tribute act to live band, we all need walk in music, or playback or interval and I think it's odd that this is not viewed as an essential requirement on modern desks,
When you look at modern keyboards, those factory Muzak demos they contain must really help to sell them in the shop,?
I would have thought by now that a digital mixer would have something along the same lines built in, a rig test demo track even, so it's checks left right main monitors etc, so while you are setting up before you even conect a mic or laptop you can have a little utility that throws a bit of noise in to your wedges and mains etc and let's you know instantly if the left mid section is wired to the right stack etc,
Cheers
Kev