A digital-to-analog converter (DAC) for an audio system in a media device, such as a portable media device or smart phone, may be operated to turn off portions of the DAC to reduce power consumption. Segments of a segment-able DAC may be powered off when the output level of the DAC is lower than the full scale output of the DAC. For example, DAC elements within a finite impulse response (FIR) DAC may be turned off when a desired output level can be obtained with less than all DAC elements of the FIR DAC. According to the invention, the determination of the number of segments sufficient to generate an output signal is based, at least in part, on the envelope of the input signal. The powering down of segments may be achieved by sending a zero code or a dump code to the segments.
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