Sounds like Parallel wiring to me, but we can't be 100% sure.
Exactly right! This is how people get burnt when driving gear below recomended impedances daily. It may be safe in SPL only because impedance will spike greatest at peak frequency, ie. the only frequency being played in a dedicated SPL system, so if you were wired for 0.25ohms you may actually be seeing 0.9ohm or something during the burp which should be safe. Try doing that daily and you won't get as much impedance rise because of the random frequencies and kaboom