This is an example of why musicians ought not mix from the stage - one of my musician friends has EQ and volume controls on his guitar. He likes to have a lot of his own guitar in his stage monitor, so he asks for the mix to be set that way. When I watch him perform, his guitar EQ is poor and his guitar volume is too loud - so the overall sound impression people get is "I like Michael but he's too loud." Well, the overall volume is not too loud, the 'bad' sounds are too loud. I've worked with the sound guys when he is performing - they EQ the guitar in an attempt to resolve those probs, then adjust the volume to a more appropriate level, and before long, Michael has, from the stage, readjusted the sound to HIS liking, and once again the audience is complaining. Michael has another guitar with no controls on-board. We never have a problem with it (it has another problem, and that is probably a discussion for another thread; it has an internal condenser mic that creates a different set of challenges).

I think this story typifies the problem of musicians mixing from the stage. Even if they have superior judgement about how a mix should sound - they are not is a position to make that judgement from the stage.