The John Entwistle Band, playing in a tiny club in 1998. I stood about eight feet from John's massive bass rig, which he dubbed "Little Manhattan" because it resembled several skyscrapers. My ears rang for 72 hours afterwards.
Second place goes to the recently reunited Cactus, whom I saw in the very same club in 2007. So loud it hurt. Ears rang for 48 hours afterwards.
Johnny Winter, 1970 Univ of Waterloo, Canada. They subsidised all gigs for students back then. Cost me the princely sum of $! to get in. .You could buy a bottle of Canadian wine for that back then....
Saw Leonard Cohen that term as well, quite a difference. Half way thru his gig his dog stood up in the middle of the stage (we hadn't noticed it as it was lying down), stretched a bit, looked around as if to say 'haven't you finished yet?', then lay right down again in the middle of the band...classic moment...
I'll give an honorable mention to a Who concert at Madison Square Garden back in the 70s. We had lousy seats, nowhere near the stage, yet sometime during the encore, my friend, who liked his music even louder than I do, turned to me and screamed "I DON'T KNOW IF I CAN TAKE ANY MORE!"
Aerosmith, without Joe Perry, but with Brad Whitford and another guitarist, playing a surprise club gig in 1980. They brought the EXACT SAME PA they were using for ARENA GIGS at the time! It literally filled the club, wall to wall and floor to ceiling. I was about ten feet from the stage for the first set and five feet from the stage during second set. Close enough to see the guitar strings vibrate and look down Tyler's throat.
I never saw Aerosmith again after that night. What would be the point?
Special mention has to go to The Wall show by Pink Floyd, Earl's Court, 1981. Loud as hell but still incredibly sharp with no distortion. 360'sound system.
The Tragically Hip at HSBC Arena in Buffalo. We FELT the music. By the end our ears could not take it, everything sounded too distorted..Gord's vocals lost in the mix.
Subsequently saw them in another venue, at a better, clearer, decibel level and they were great.
Another great Canadian band that never quite made it in America or elsewhere.
The Sex Pistols, July 20th 1977, Oslo. I actually thought my ears were bleeding. They were not. But I think that's whan my hearing was slightly reduced.
The Ramones at the Channel Club in Boston. A small venue, but they had every amp they owned on the stage and I was about 10 feet away from them. You know how when you are swimming underwater in a pool and you can kind of hear people having conversations above the water? That's what my hearing was like for hours afterwards.
The Black Crowes at the Olympia, Paris, 2001. 1st row just in front of Rich's stack. My ears were hurting even before his amp was fed to the main sound system. That larsen at the beginning of the show really spoiled the show for us, and we almost had to leave. We were relieved when the show was over. It may have been because they didn't have an opening act to train the ears.