Systems and methods provided herein decrease an idle channel noise floor and reduce power during an idle channel input for low power audio devices that include a digital pulse width modulation (PWM) amplifier having a noise shaper. An audio data signal is monitored for an idle channel condition. The noise shaper performs quantization of the audio data signal and uses noise shaper filter coefficients to shape noise resulting from the quantization. Predetermined values for the noise shaper filter coefficients are used to shape the noise resulting from quantization while the idle channel condition is not being detected. The values of the noise shaper filter coefficients are reduced so that the values move toward zeros, and the reduced values of the noise shaper filter coefficients are used to attenuate noise resulting from quantization, while the idle channel condition is being detected. The noise shaper filter coefficients are returned to the predetermined values when the idle channel condition is no longer detected. Alternative embodiments are also provided.