When I was younger and stupider than I am now (believe it or not), I connected a bunch of speaker cabs in parallel to a poor Tangent mono power amp that was capable of 200 watts into 4 ohms.
I knew better, but stoned teenagers at a stoner party gig will do the craziest things.
The total impedance at the speaker terminals was like .2 ohms.
Fried the output stage but good in no time flat, dumping some loud 60 hz into the speakers.
Gig over.
;D