hooking up subwoofer to 2 channel tube amp

I see.  So you are saying I need something like a spade plug at the base of the out and keep my banana plug into the terminal itself so there are actually 2 speakers (one main and a sub) attached to the same place?  Do I have that right?

Call Crutchfield, they'll be able to explain it all.

Thank you. I'll give them a call if I can't figure it out, but I think what I said above is correct.

I see.  So you are saying I need something like a spade plug at the base of the out and keep my banana plug into the terminal itself so there are actually 2 speakers (one main and a sub) attached to the same place?  Do I have that right?

You got it right!
https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/43524898376238682/filePointer/4352489837...
Any combination will work.

Check out REL subs.  They connect through the speaker outs on your amp but only augment the base without involving a crossover.