It looks like the HX stomp only has a single FX loop that can be either mono or stereo, so you cannot have both of the H90 paths being used as separate FX loops.
What if you used one of the H90’s paths after the HX Stomp instead of before? That would allow you to have more flexibility with the drive placements, and then the other path of the H90 can be used for post FX like delays/reverbs etc.
