Desktop Note number mod - 12 voices?

I’ve been going through the S6 manual and I can’t quite conceptualise why key tracking & x-fade reduce the polyphony to 6. It says its due to there only being 6 pairs of VCAs for the mixer, does it mean a CV mixer?

In any case, I very often like to use arbitrary amounts of keytracking on filters as well as negative amounts so I’m happy that I believe the Desktop allows for this.

My question is; when assigning note number to e.g. filter or any other parameter in the modulation matrix do you effectively only get 6 voice polyphony as well? Does it switch to binaural? What happens?

Thanks