An audio device may include an electrical terminal for coupling a transducer device to the audio device and an audio circuit for generating an analog audio signal coupled to the electrical terminal. The audio circuit may include a pre-amplifier stage, an amplifier, and a gain selector. The pre-amplifier stage may apply a selectable gain to an audio input signal to generate a pre-amplified analog audio signal, wherein the pre-amplifier stage is powered by a first power supply. The amplifier may amplify the pre-amplified analog audio signal to generate the analog audio signal, wherein the amplifier is powered from a second power supply isolated from the first power supply. The gain selector may select the selectable gain based on a level of the first power supply, such that a difference between the second power supply and the analog audio signal is more than a predetermined headroom threshold voltage.