384 per HDX card as I understood the video.
https://www.pro-tools-expert.com/hom...d-macos-mojave
For HDX Users - If you an HDX owner then with this new version of Pro Tools the maximum number of simultaneous audio tracks for each HDX card will go up from 256 to 384. If you have an HDX3 system that will bring the maximum number of simultaneous audio tracks to 1152. There will be no extra charge for HDX users. The voice count is dependent on the number of HDX cards you have. If you have 1 card you will get 384 voices, 2 HDX cards will give you 768 voices and 3 HDX cards will give you 1152 voices.