 While the Prosonic featured cathode bias in the Class A mode and fixed bias in the Class AB mode, not all class A tube amplifiers are cathode-biased, and not all fixed biased amplifiers are Class AB.Fixed bias amps, however, require lower B+ Voltages to stay within the Plate Dissipation of the power tubes used; Cathode biasing "throws away" this voltage using conventional Higher Voltage power supplies.A channel-switching amp, the Prosonic offers a clean channel that features a blend of traditional Fender sounds with the influence of Vox amplifiers, frequently attributed to the Class A mode.