Well, b/c the H9 has two footswitches rather than three, adding a single button or a three button aux switch would let you use the performance switch which for the reverb algorithms lets you toggle between two preset settings in a single preset and for the delay algorithms toggles the repeat function. If you get a three button aux switch, people often use the extra switches for banking down, launching the tuner, tapping in tempo; all of these things can be done on the H9 itself but not necessarily with a single footswitch press…
