You know, 42V DC for a short period of time (long enough to blow a rail fuse) won’t do anything to an SP2. And it would probably drop to the mid 30’s anyway at that load. A cute little 6.5” would turn to charcoal. I don’t usually DC protect my “little” amps unless it just happens to be cap coupled. I had a TIP41/2 based amp running on +/-25V that fried trying to drive 2 pairs of speakers with it (surprise, surprise). Didn’t hurt either pair when it went pop-hummmmmm and shoved the VC’s forward. 8’s and 10’s with 1.5” VCs.