Yes, this is possible. Enable a stereo insert and place it at the very end of the chain if you would like a duplicate of the output signal with all of the H90’s FX processing. Set the Insert Mix to 50% and you should be all set, the same signal will be sent to outputs 1-2 and 3-4.
https://cdn.eventideaudio.com/manuals/h90/1.8.6/content/edit-modes/routing.html#insert-routing
