You are the second person that mentioned about the bass issue in the past two weeks. (Don't get me wrong, there's nothing wrong with that.)
I had stated on the other post that owners and reviewers alike have all pointed out this is a strength with Pass amps. I've certainly feel the same with my X350.5 after it replaced the ML 333 I had for 8 years.
So, just thinking aloud, could the issue be caused by something else other than the amp? Maybe not enough power with the X250.5 to drive the 802D as you indicated? Maybe room issues? Speaker placement issues? Impedance mismatch issue?
In terms of selection, maybe checking with Wilson to see if the XA160.5 would be powerful enough to drive the Maxx? How about the XA200.5? Maybe also check with Pass Labs to get their feedback as well?
There's an article last year in either TAS or Stereophile where they compared the XA160 and X600 (or X600.5), it might be worth to take a look.