I had the same problem in the late '70s with a jerk upstairs who held a dance party every weekend. Sounded like an army marching to music across the floor upstairs. I already had Polk 10 speakers (I didn't KNOW any better, I tell ya!), a Thorens table and a recording of the brand new Telarc 1812 overture. All that remained was to borrow a Phase Linear 400 from the Tech Hi Fi I managed. Skipped the music and went straight to the artillery. I was afraid the windows in the living room were going to blow out they were rattling so badly.

Same result - peace, perfect peace. Speak softly, but carry a big sonic stick.

PS - Sadly, I think my neighbor must now be an inflential member of the Hi(nd) End, as RMAF had an awful lot of people doing the same crap. Deafen to impress. *sigh*