Keep in mind the H90 does not have a “BOTH” mode like the H9 where you can connect both a switch and an expression pedal simultaneously into the same EXP input. You would need to connect the TIP end of the SP-H9 to EXP 1 for expression and the Ring end into EXP 2 for the switch to work simultaneously. If you just want to use the SP-H9 as an expression pedal, then yes, you can just connect the TIP side to EXP 1 leaving EXP 2 available for a dual aux switch.
