I don't know if we've covered this already, but I was just thinking about a couple that stand out in my mind.
One was a concert by Bill Chase's last group. Deafening.
But the loudest.....and this was not "fun loud", this was PAINFUL, stick-your-fingers-in-your-ears loud....was Weather Report in the late 70s, the Jaco/Erskine edition. It was a great concert, but there was no reason for it to be so friggin' loud. It definitely "harshed my high" (it WAS the 70s, you know....I think that was a "brownie" event, IIRC).
A good loud concert was the Chicago Symphony in the mid 70s performing Holst's Planets. That was an awesome brass section.
Now will someone answer that damn phone already?