OK, my 2cents
And to go along with quack, MJ and such it could be a bad speaker try, testing one at atime
Put a Voltage tester on the terminals see if there's continuity, see if thees a short internally. Maybe, one of the wires came loose, maybe it even fell off and is now shorting out within.
Maybe they we're drinking the night before and hooked it up in Serial. there's only four screws per driver nothing to it to check them out

Pioneer sc-1525
M80 HG Cherry