Do high dollar mono blocks truly improve the Sound Quality over the mid tier amps

Re original query:  In general, yes.  Price will vary by intent or depth of pockets...

I see "zero" acoustic treatment in a room which appears to be very lively with lots of hard, reflective surfaces. You may not even know how good your system can sound presently. I'd suggest starting there before spending another penny on equipment.

The OP is asking if higher end monos "could" be a significant sonic upgrade.

IMO absolutely yes is the only answer, but the real question is how much is the OP prepared to spend, because price is MORE OFTEN THAN NOT an indication of ultimate quality.

Example: the difference in sonic quality and price between the Deltas and the new 7 series from Soulution is vast.

One way to be sure of the pairing is to ask Wilson which amps they use when they display/demo at Munich and/or Axpona. They'd know better than anyone here how to get synergy with their speakers.

You have some very nice equipment. What do you feel is lacking in the sound it makes? Perhaps room treatment is the direction you should go at this point?

@OP Replacing your XP-27 with an XP-32 would probably be a better value improvement.