No Sub-Mojo

You can use a set of your tape-monitor "record" jacks to feed your subwoofer. However, these are usually fix volume output (also called "line level") so the subwoofer you attach them to must have some kind of volume control (Note: The Pre-out jacks are variable loudness). It doesn’t have to be remote control but line-level volume is "all the way up" that is, really loud, so you have to have a way to turn it down to sane levels. Why don’t you sell enough of your 12-13 subwoofers to buy one (or two) with remote control?

Dweller, I think you were correct in your earlier post about the switch to select normal/separated.....to activate the outputs, the switch has to be set to 'separate', but that's where the caveat from my tech kicks in; it will also disable the amplifier output. Selling used subs is slightly more profitable than selling a used Yugo (who remembers those?). I only have two subs sitting idle, an Outlaw LFM-2 and an Orb Super 8. Good little subs, but not worth much on the second-hand market. I may just forgo the sub hook-up entirely because the speakers will have a 10" woofer, giving sufficient bass. Thanks for all of the suggestions and comments.

Good luck!

@discnik

Maybe you can try connect the sub to 'MAIN IN' instead of 'PRE OUT' while the switch is at 'NORMAL' position. If no signal output to the sub, next thing to try is using a 'Y' adapter connect one end to 'PRE OUT' and the other end to 'MAIN IN' to loop the signal back to power amp section. The sub connect to RCA female end and set the switch to 'SEPARATE'.

https://www.amazon.com/Adapter-Female-Splitter-Amplifier-Subwoofer/dp/B07LB5CCTB

That makes sense...I'll give it a shot. Thanks!