Best CMMR with DIY Mic Input XFMR

[reinw33]

First,

thanks to those that have uploaded Transformer disassemblies and schematics.
Many were lost on the forum but a few I was able to save and learn from it.

Being about to have all parts arrive, it'd be time to assemble my first few DIY Mic-Preamps and modules.
I wondered about the factors of good Common-Mode-Rejection-Ratio and Hum reduction with DIY mic input transformers.

Pearmalloy cores plus pearmalloy shields are an important factor of course.
But...



Question 1:
In terms of improving CMMR performance, would it have any benefit to reverse the winding direction of the center-tap of connection T2 to T3 terminal on on the input side of the transformer? Please see image.

Question 2:
What else could be suggested to improve or to have the best possible CMMR and/or hum rejection? Better as in, better CMMR performance than a differential amp, if possible.


I live in Germany but still find difficulties in finding places to order suitable input transformers domestically.

Thanks.