You can control the overall output volume of Riverside with a connected expression pedal by setting the pedal to Volume Mode. In this mode, the expression pedal will control the volume with a logarithmic audio taper for smooth control over the output signal.
In Volume mode, the LEVEL knob sets the highest volume level for the TOE down position of the expression pedal. Also, the highest TOE down position of the expression pedal will correspond to the setting that the LEVEL knob was saved to for the Favorite setting.
NOTE: A connected expression pedal will still control the volume output even when Riverside is bypassed if the pedal is set to buffered bypass mode.