Sounds like a problem with the venue wiring to me. A couple of brief anecdotes; events from a few decades ago..? I was installing the lighting fx in a brand new disco complex. Cabling stuff up under the dj console, I had an intuition. No reason for it; just thought it a Good Idea to test the side-by-side sockets I was going to use. Both read 220 volts, as they should, but I also decided to check the tension between them, and there was the surprise. They had been wired from different phases, and so had 380 volts between them..! Plugging connected stuff into both of these would have certainly 'fried' something, possibly the tech (me..!) or a DJ..! Why did I check this..? No reason, it was (up until then..!) not part of my routine; just a hunch. Lucky escape.
Less so for my unfortunate brother, 'roadying' for a local variety band. Plugged in the PA into the house sockets, turned it on, and smoked it all. The sockets were unmarked, but were 380 volts, not 220. The stack of Peavey 800W PA amps blew, taking every single HP with them in the JBL 8 x 15 columns. No FOH for the show that evening, and it took me several weeks to firstly order and receive, then install, all the elements that had suffered; there were a lot.
Moral of the stories..? Don't trust house wiring, ever. It's rare that it kills, but it only needs to be once...