The problem is more often with the Venue = For FAR too long the assumption had been that ANY entertainment would be Amplified , so no one things about exactly what effect Carpets , Wallpaper , and curtaims can have on acoutics , especially deadening the upper frequencies !
This , coupled with your average punter only being used to LOUD music , means that if you work Un Amplified , the Vocalist cant even TALK the following day !