I leave the guitar amp to the guitarist (except for frequently yelling "turn it down" with some of them!
Originally Posted by ecc83
PA amps and speakers are a different kettle of fish from domestic stuff (where I'd agree about being more careful with matching the specs). My "double the power" advice is for PA work only with gear designed to be used that way.
I now only have a small PA anyway and have got around this issue with powered speakers. However, I still work the same way with those--I set up the gain structure on the mixer as I want it then turn up the input attenuators on the speakers to the level I need. For the size of place where I typically use my gear (there are only two or three venues where I tend to work and most of it is musical theatre) this means the knob about half way up for a plenty loud signal and lots of room before clipping.
That's what I do. I drink and I know things.
-Tyrion Lannister (and Bobbsy)