PSU Voltage 160v vs 120v what am i missing?

Hi guys.
I am done moding my SmPro MC03 (Nady 1050, Apex460 etc.)

I changed tube for 12ay7, capsule, transformer, removed some caps and decided to go with switch just for fun to be able to change between 160v and 120v.

And now i'm puzzled. I recorded several drum takes, guitar loops, vocals, pink noise, silence through speaker into mic, as loud and quiet possible to be able to critically compare 120v vs 160v without having my ears trick me.

120v has a tad lower output, just a couple db. Otherwise takes cancel each other perfectly in phase cancellation test. I tried even different capsules. They are identical! Even same noise floor.

How is the capsule backplate charged?  Resistive divider off the tube capsule, or resistive divider off HT?  You don't want excessive voltage on the capsule.  Typically 40 volts, some tolerate 60 volts, no more.  (Some of the older mics tolerate more capsule voltage but the user must consult the manual first.)  Run the HT at the design voltage.  Better to work low and sacrifice the couple db.  Run the capsule high and run the risk of membrane collapse (or arc) the capsule.... $$$...

Don't expect difference in sound with CCDA circuit, with plaate follower it would be more audible.
These capsules can handle 100V without any problem. Also if there is (and there is if you didn't mod this mike) few bugs in the circuit which affect badly response in different ways, then this mike will be same badly sounding unless you will drop voltage to very low values (starving plate) - then it would be much worse sounding.