Great topic. One of the bands I belong to plays a regular gig where, despite our guitarists' tiny 18W Honeyboy amps, the bar manager always wants us to turn the volume down. Our next rehearsal is intended to run through the set at very low volume to see if we can do it, which we know we can, then take those settings to the next gig at that venue.
I'm looking forward to it.
I played a huge PA gig with a rock band on Friday and the onstage volume from the monitors was shockingly loud. We did ask soundperson to turn them down but it was all a mush. Punters did say the FOH sound was excellent so who are we to complain?