misternice, I've left comments to those who know more about electronics than I do. But now I must ask, have you experimented with VTA? Some cartridges with some records can sound bright (as you reported) when set up with the standard parallel to the record alignment. Lowering the tonearm a bit to tip the cartridge back can sometimes help.
I guess it depends if there was any music in those 90 records you'd like to retain.
I guess it depends if there was any music in those 90 records you'd like to retain.

