I use a mustang 2 as a monitor on the platform.
I go out of the the XLR's to the main house sound and use the 1/4" outs to the mp3 IN on top of the mustang.
Have the amp blowing right up at my head. works like a charm.
i usually keep it low volume just to add some low end so I can still hear when the orchestra gets loud.
too much volume and it fools me into thinking i am louder out front; so i tend to lay back and now play as boldly as i should.