An apparatus comprises a digital to analog converter (DAC) circuit configured to receive a time-varying a digital input signal and convert the digital input signal to an analog output signal, an output amplifier circuit operatively coupled to the output of the DAC circuit, a peak detector circuit operatively coupled to the input the DAC and configured to produce a signal envelope of the digital input signal, and logic circuitry. The logic circuitry is operatively coupled to the peak detector circuit and is configured to detect when the signal envelope satisfies a specified threshold value; and to adjust a drive capability of an output amplifier circuit of the DAC circuit according to the signal envelope.