The BOSS EV-30 brings powerful real-time parameter control to the many BOSS compact pedals equipped with expression pedal inputs.
Both models also provide an Expression output for use with expression-compatible amps, effects, and even synthesizers.
The low-impedance BOSS FV-50L is a stereo volume pedal that can be used for a wide variety of purposes including keyboards.
It is compatible with half-damper capable keyboards, and it can also serve as a standard pedal switch (for sustain, etc).
The Roland DP-2 can also be used for things like punch in/out on Roland/BOSS recording gear.
Using this controller you can easily activate all the main functions (Start/Stop, Intro, Basic/Advanced, Fill in to Variation, Fill in to Original, Original/Variation, Ending).