Another thing in the same realm as the two way connection between a DAW and MPE or Poly-Aftertouch on the Hydrasynth, there is also a two way high precision connection to virtually all the controls accessible on the Hydrasynth by a DAW that is capable.
This is done with a trick that was added to MIDI a number of years back, called NRPN. NRPN in a nutshell is a way to combine four regular MIDI CC messages and make a new enhanced CC message with much greater precision, and many more separate messages.
There is a separate reference that ASM put together with the specification. But since it works both ways you can also manipulate almost any control on the Hydrasynth and view the NRPN code it creates, rather than studying the reference manual.
This permits you to do some amazing things, like create and navigate infinite sized wavetables, or change the Mutants on a voice on the fly and manipulate all the parameters that are not included in the Modulation Matrix, like all the parameters in the Mutant that was just changed. And on and on !
The possibilities are mind blowing and mostly little explored, including by me.