I use to do security at a couple of venues and many times I was up close to the stage. Loudest was a stoner band called Sleep. The guitarist and the bass player were each playing through three Orange full stacks. And they weren’t for show, all were plugged in. Painfully loud even with ear protection. Even the house roadies were complaining. Second loudest concert I saw was Motörhead and Alice Cooper. I think it was a competition to see who could be the loudest.