 Its most unusual feature is the switchable rectifier and power amplifier bias scheme, allowing on-the-fly changes of operating mode and output power (as well as subjective tonal differences).This feature, originally found on Randall Smith's Mesa Boogie amplifiers, allows the Prosonic to achieve a versatility very rarely seen from mass-market instrument manufacturers.The Prosonic's rear-mounted RECTIFIER/BIAS switch lets the user select from the following three options