Hanging speakers from cables could be a bad idea. If the speaker hits just the right notes then it would excite the tensioned cable supporting it and cause it to vibrate.
Back in the 70's, I met a guy named Tom.. He was in a band and played guitar. The story goes, he went on to "higher" education studied music theory using keyboards mostly... thought he understood it all got bored and became an airline pilot.
The interesting part and I have seen this happen... he could find the harmonics of a structure (the house we were partying in) and if he wanted to shake the sucker to the ground... it was amazing! He would just play around till everything was shaking. If I recall correctly, he had a sun amp. would turn it towards the wall and just go at it.
or it was the acid and a good story!
