Of course the soundproofing couldn't stop all frequencies from escaping, particularly with the amount of power involved at this gig.
Eventually someone realised what it was that was making things rattle all over town and dispatched a security guard to serve a noise abatement order.
Dave pointed to the large black guy at the mixer on stage and said that was where the volume control was.
Just standing by the auditorium door was enough to produce sweat from all pores, such was the heat and humidity emanating from the five hundred or so punters inside.
Faced with having to wade through this mass, Dave having lied there was no other way backstage, Rent-a-Cop simply gave up and left.
I have heard of attempts to abate the noise of a rugby match, with a similar lack of success.

Safety in numbers.