Hello treillw,
First, since you are new to the H90, make sure you’re on the latest firmware. Be sure to download the latest version of H90 Control and update the pedal. Since its release, there have adjustments to the gain structure that may play a role in what you’re experiencing.
From factory, the pedal is set to operate at instrument level. What is your signal chain like? Are you going guitar into H90 into an amp, or do you have it in another position?
