This is an absolute hard limit for me, though I am not projecting my preferences on anyone who might think otherwise.

While I respect the professional/client dynamic in ProDomme session (no sexual contact), there is still an element of eroticism and sensuality in the sessions that I have experienced. I believe that the majority of subs here would hopefully agree with that observation. NT, CBT, anal play etc. all have an erotic and/ot sensual element to them.

Introducing another male into a session would, for me, greatly reduce that eroticism and sensuality. Also, and again for me at least, my highly competitive nature would kick in pretty quickly, making it impossible for me to recognize a male dom as my superior.

Just wouldn't work for me but I say go for it to those interested in having that experience.