Ortofon A-90 Tonality Question

I got an A-90 about two weeks ago to replace a Koetsu RSP. I have it dialed in as best as possible and find that it does almost everything well in my system. I have the cartridge body level in terms of SRA, VTF is 2.2 grams and azimuth was measured with a DMM/test record.

The problem I am having is a leanness in the midrange, especially on vocals. There is a bit more sibilance than I would expect and there is a lack of richness in the lower vocal registers.

This may be that I am used to the Koetsu sound but based on observations here and on AA this doesn't seem to be a general issue and it seems more pronounced than I would expect.

Associated equipment is VPI HR-X/JMW 12.5 with Discovery wire (run from cartridge clips and soldered to phono stage input), Herron VTPH-2 phono stage, very modified Cary SLI-80 amp and Merlin TSM-MMi speakers. Interconnects are VH labs DIY silver and speaker cables are VH Labs Chela.

Based on general specifications the JMW arm should match fairly well to the A-90 but the A-90 performance seems to have some tonearm dependence. Also, there are only about 25 hours on the A-90 so it change over time.

Anyone running an A-90 in a VPI arm or have similar results in other setups?