Distortion mystery -- MC cart mistracking? / transformer / head amp input saturation??

Could use some input from the experienced high end record spinners here....

Context: VPI Classic 3/JMW 10.5 metal arm (damped w oil)/ZYX R100H --> Audio Note ANS2 xformer (low gain setting) --> Jasmine/Mockingbird modded LP2.5 DU active phono stage on MM 47kohms setting... anti skate off.

Recently switched cartridge over from my Audio Technica ART 9 cart to this ZYX R100H to check it out (bought ’low hours’ from a well reputed A-gonner). On some records, am hearing an occasional distortion in the vocals and mid-upper piano range... usually on transients of increasing volume. I first thought it is mostly at the 1st half of the record... but it seems like it happens throughout the sides of records where it happens (...I know the VPI jig sets minimum tracking error at end of sides). Seems to happen on records that play a little ’louder’... as opposed to audiophile records where volume levels are lower.

Checked ZYX alignment using the VPI jig couple times... am right on. Tracking at 1.9 grams, VTA level. Azimuth good via the balance beam pole on headshell. Tried different tracking forces - up to 2.1 grams, raised and lowered VTA - still distorts. Using Zerostat/CF brush on record, and Zerodust on the cart tip. Record washed with Okki Nokki. Very good hygiene I think.

As an experiment, I removed the AN transformer, and ran the Jasmine in MC mode at 100 ohms loading, and the distortion seems to have lessened greatly. Could the AN transformer be overloading the MM input at the phono stage? But then why just distortion on transients?? Many other loud passages do not distort.

By the way, I have no such trouble in 200-300 hrs with the ART 9 cartridge... just pure musi, clean and gorgeous... just hearing this with the ZYX.

Thoughts/comments/ideas??

Thanks in advance...