I agree that the room can make a big difference to the sound. But I always had my top speakers set up high so the sound went over the crowds heads and was crystal clear to the back of the room. Because I am a perfectionist I once made the mistake of listening to a so called expert who told me my Technics mixer didn't have any mid range adjustment. So I went out and bought a very expensive mixer which also needed all new cables with XLR's. What a disaster. The mic was so loud that it was either off or blowing the speakers, and one Chanel was louder than the other (couldn't sort it all night), and it fed back all night. Sent it back the next day and went back to the Technics. If it ain't broke don't try and fix it. You can have the best gear in the world, but if you haven't got the ear to set it up properly it'll still sound shite.