My questions are: If I want to be able to move my dry/wet effects (front/back of the amps) anytime I want, is my diagram correct?
Your diagram is correct for a Pre/Post configuration using the H90’s Dual routing mode. Keep in mind you will only have control over the H90’s preset positioning, not your dry effects chain before the H90 or the wet chain after the H90; those will stay in the same position no matter what. If I/O 1&2 is Path A (PRE) and I/O 3&4 is Path B (POST), you can always place an H90 gain-based effect last in your dry chain or first in your wet chain. Or, you can put a wet effect last in the dry chain or first in your wet chain. Or, you can put two effects in parallel last in your dry chain or first in your wet chain.
I have another stereo delay pedal, where can put them following the H90’s dual routing tutorial?
If we still go by your diagram, I would place it before your reverb.
I also have channel 2 not in use for my EQ, how can I leverage them?
It depends where you need the EQ the most. Right now, it’s last in your dry effect chain which is entirely mono. You could wire the second channel of the EQ before the compressor. Using a mono EQ after the stereo output of Path B doesn’t make sense.
