How to use multimeter

Could somebody guide me through a process?
I want to measure an output signal on my power amp to make sure it's equal in both channels ( I suspect it's not).
My idea is to play mono signal (pink noise?) and to measure voltage on amp's speaker terminals with speakers connected.
Please tell me a correct way to do it, I certainly don't want to damage my amp, and want to make sure I'm measuring what I suppose to measure.
If you think I know what settings on multimeter I should use- you are wrong, I don't.
That's what I mean: please guide me through.