A dynamic dual-mode digital pedal that controls the volume or amp/effect parameters on Mustang GT, III, IV and V amplifiers and on Mustang Floor multi-effects unit. Switch between "Volume" and "Expression" modes by stepping on the toe-end of the pedal. Red and green LEDs indicate the mode in use. The Volume mode—indicated by an illuminated green LED—controls the master volume or can be turned off. The Expression mode—indicated by illumination of the red LED—controls most Mustang amp and effects parameters, such as frequency and modulation effects.