I have some I got from a seller in China that are pure copper with double silver plate, and some copper WBTs I got when on a deep sale some time ago, but have not put them in yet. I have been doing a progression of mods and been pretty disciplined to wait to digest each one before the next. But I figure between the CSP3 and Torii, and my DAC, I can use them all, setting up excellent choices for fine-tuned mixing and matching.

Having heard notable differences/improvements with nice male RCAs on ICs, I expect the same with these.

Have you looked at vyokyong's thread on modding the ZMA.

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1409130590

Interesting thread to me. Somewhere in there are his evaluations of some WBTs he put in, I think both in the Decware switch box and ZMA.