Thanks for the links Mah. No Soundcraftsmen manuals, but the Crown was informative. I found out I can mono bridge it with a couple of internal jumper wires and a resistor or capacitor (can't remember, but won't try it nor running it at 2 ohms).
For fun I spent about 5 hours and went through every crown amp on Ebay and looked up each in the crown obsolete section webpage. It was interesting, but I can't make heads nor tails from it or figure out which would be a worthwhile amp to seek out. I also notice that there appears to be no rhyme or reason for the names, lettering, or numbering of their amps. Looking at the prices everyone wants for used-up gear, and having never bid on anything on ebay before, I think that the Parts Express Crown XLS 1500 that was on sale in December for $350 sounds like the best bet for a sub amp.
Crown XLS 1500 DriveCore Series Power Amplifier | 245-502



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