One thing we used to do during sound check was go out into the hall while playing to hear what it sounded like. At least one of us would wander around the place and see where sound was bouncing. An empty room reverbs differently to a room full of people but and empty room can still give you a good idea what the fans will hear. The other thing we learnt early on was, never trust a sound tech wearing headphones. It's one thing to listen to some of the sound check through headphones, it makes it easy to separate lines, but at some point they need to come off. It used to shit us when we turned up to a venue tech, not our own, and the prick thought he could get good sound through cans because he knew the venue.
