That is a warm rig going into speakers that are not known for being bright. I would need to dig into it, sometimes the wrong impedance curve on a speaker can make a tweeter sound hot when paired with a tube amp. You might find switching to a neutral SS amp. Naim, AVM, AGD come to mind for me. You should be able to borrow or buy on an amp on a return policy to test this.
how is your room? Damping matters and if the room is underdamped it could be creating this issue.
Finally, If you are looking for a more “English” sound maybe Harbeth or Wilson Benesch will solve the issue. You ought to be able to find a used pair of used 40.2s or the P2.0s in a similar price range.