The amps master volume is in the series effects loop.  The H9 is the only pedal in the loop  The other algorythms allow the Master Volume to still control the volume.  I have teh Kill Dry Audio in the General Settings set at NO.   When I put this in Yes, the the H9 goes silent.  Not sure why the App states why the Kill Dryis normally enabled when the unit is connected in the amps effects loop.

I apologize but I am not an Audio engineer.