I think you are on to something with the high pass. I haven’t ran room perfect again yet but set my crossover at 60hz both the subs and the speakers. Sounds better for sure and more dynamic. Gonna enjoy it that way till tomorrow and re run the room correction and see what that does. Sorry to hear about your JL sub. They will fix anything to do with a V1 Fathom for $450. I sent the amp in and they replaced a bunch of caps with the V2 caps and sent it back within 2 weeks. It sounds better than it ever did now.
The guy I bought them from gave me a room sweep printout and they started falling off the shelf at 55hz a little bit so I think 60 is good. May play with that some more.