And now… I cut the foam a bit.
-Hiding, like, 3 millimeters from the top and rear of the driver, gets rid of the 4khz-to-8khz plateau, so they’re more neutral (Harman neutral) now. That’s my goal.
-Cutting the foam at the front also adds “front” soundstage, I think!
-Cutting the foam at the bottom definitely gets rid of the muddiness. Even at dangerous, dangerous volumes. Planar bass/kick slam is back.
(And yeah, I also have HD58Xs. That’s what I used for comparison – I love these.)
This just makes my T50RP perfect for me. 
(Right driver)
That’s all folks! 