grand funk railroad at boutwell in early seventies. ears rang for 3 days after that one.
Although I can't find any record of it on the interwebz, I saw Blackfoot, Molly Hatchet and I think .38 Special in Boutwell sometime in 1984 or 1985. We stood within an arm's length of the stage and speakers. I couldn't hear out of my left ear for three days and am sure I sustained permanent damage from that. Even at the back of the auditorium it was one of the loudest places I've ever heard a show.