Using an Expression Pedal together with MIDI - Morningstar MIDI Controller - YouTube
SOURCE AUDIO Dual Expression Pedal for Soundblox, Soundblox
Amazon.com: Zoom G1X FOUR Guitar Multi-Effects Processor with Expression Pedal & D'Addario Accessories PW-CT-9V DC Power Adapter – Minimize Need to Change Batteries on Pedalboard and Other Devices Requiring 9V : Musical