You can still adjust VTA up with shims. But from your description of the sound that will not help. If you already have some shims in there you could take some out to lower the back of the arm.
In the short term a warmer cart should work but in the long term I would look at upgrading your preamp/phono stage. From the one small review I could find of your PS Audio 4.6 they described the sound as having good tension but being a bit too forward and brash.
Yes, I agree. If I could find a nice tubed preamp (with phono) then that may solve my problem as well. Problem is I can't do both and the preamp would cost considerably more I think.