Can you be more specific with what amps you are using and what you are trying to achieve with the setup? You always want the FX processing to be in the amp’s effects loop and panned between both amps? You could try something as follows:
- Connect guitar to amp 1 preamp input
- Connect amp 1 FX send to H90 input 1
- Connect H90 output 1 to amp 1 FX return
- Connect H90 output 2 to amp 2 FX return
You could also do a dual routing mode pre/post setup if you’d like some of the H90’s effects to be before the preamp:
- Enable Dual Mode on the H90
- Connect guitar to H90 input 1
- Connect H90 output to amp 1 preamp input
- Connect amp 1 FX send to H90 input 3
- Connect H90 output 3 to amp 1 FX return
- Connect H90 output 4 to amp 2 FX return
- Use the routing mode on the H90 to determine which presets are on Path 1 or 2. Presets on path 1 will be in mono before the preamp, Presets on path 2 will be in stereo in the FX loop
- Turn kill dry on for whichever presets are on Path 2
- More info can be found here https://cdn.eventideaudio.com/manuals/h90/1.8.6/content/setup/pre-post.html
