Hi Rex,
Yes, this is possible using the H90’s insert routing.
- Make your connections as described above
- Press the Routing button on the H90 to access the Routing menu
- Turn Quick Knob 3 clockwise until it enables a stereo insert
- Turn Quick Knob 2 to place the stereo insert at the end of the H90 signal path
- Turn the Perform Knob to get to the 2nd page of the Insert parameters.
- Adjust the Insert Mix to be at 50% (if you don’t do this, there will be no output on 1-2)
- Adjust the Send Level to change the volume of the signal for the stereo power amp/cab.
More info about the insert routing can be found here: https://cdn.eventideaudio.com/manuals/h90/1.9.7/content/edit-modes/routing.html
Let me know if you have any questions or issues with the setup.
