The H9 will accept an expression pedal and one single aux switch, or one triple aux switch, but not both. Using an expression pedal and one aux switch requires a 1xT/R/S > 2xT/R/S "Y" splitter. You could install a single momentary switch in the toe of an expression pedal – some pedals have an active/inactive or A/B switch in the toe that could be replaced with a momentary switch and wired as an aux switch.
