Because it is hard to imagine enough output tubes to handle even 2 amps of idle current, a hybrid Circlotron amplifier is shown. The output stage runs in pure, real Class A and it will get hot even with its small solid-state rail voltages. The first tube provides all the voltage gain; the second tube, the phase splitting; the MOSFETS, the current gain; the Op-Amps, the DC servo housekeeping. Should one fuse blow, the opposing Op-Amplifier's positive power supply connection is lost and its output voltage must collapse to zero volts, which turns off the opposing MOSFET.