You could also serve the 16 channels of IO from MTRX Studio 2 up to the Dante network and not connect it to the HDX card at all.
I say this next bit not for the OP but just as a general point for anyone thinking about how to structure their MTRX/MTRX Studio install.
It is obv just my personal opinion.
2x MTRX Studios is not the way I would do it.
You can expand a single MTRX Studio with any number of Dante expanders, some of which sound as good as the MTRX Studio.
All the way up to 64 channels of IO.
In my full fat MTRX the sky is the limit in terms of routable channels- thousands of them if I need to.
This is what I have attached to the MTRX:
I also have a Rednet PCIE-r, Ferrofish Pulse 16DX, Eventide H9000, Lynx Aurora N 32 Dante and a bunch of computers using DVS.
The whole point of having Dante on an audio interface like the MTRX/MTRX Studio is to be able to expand it in this manner.
2x MTRX Studios gives you the same conversion across the board but that isn't really such an issue.
I have converters from 5 or 6 different companies and they all sound fine.