@fred60 ,
"I think you are right not to spend too much, as Class D amps (I think all subs use Class D) can’t be repaired once they fail. I spent about $2,500 on a Paradigm sub for my home theatre setup and it failed after about a decade of use. It’s why I’d never buy active speakers. Who wants to buy a pair of speakers that will only last a decade? JMHO."
I sent my JL F113 amp into JL to get fixed. It's a flat $450 charge and they put a bunch of new caps in from the V.2 line, replace anything broken and replace anything that is known to be problematic or doesn't measure out. I didn't think that was too bad a deal. If you send the entire sub in they will even replace or re cone the woofer if there is any degradation. Super responsive emails and really great to work with company IMO. I could not believe when I looked up the F113 current line and they are 6k! At that price I'd say they are probably overpriced! I think I paid like $3,500 12ish years ago. Guess my point is that class D can be repaired like any other amp.