Abstract: An audio amplifier has a collapsible power supply coupled to an audio amplifier circuit to drive voltage rails of the power supply in an inverse relationship to the power consumed by the amplifier circuit. A variable gain input stage includes a linear potentiometer gain control followed by a gain stage and buffer to drive separate bass and treble controls, summed before appearing at the input of an integrated circuit amplifier. The main voltage amplification is provided by an integrated circuit, supplied with power by common base circuits to isolate the integrated circuit from power supply induced distortion. Staggered output stages are coupled to the output of the amplifier, the earlier stages having a longer duty cycle and light duty factor, while the later stages having a shorter duty cycle and heavier duty factor. A voltage doubler sensing power drawn by amplifier to modify voltage rails available at the output of the amplifier circuit.