An audio class D converter has nonlinear distortion provided by power stage. In fact, the PWM inverter is influenced by the switching dead time introduced by the power output control system. If output capacitance is added, the audio quality is improved. In this paper the interaction between the dead time effect and the output stage capacitance is investigated. At first, each effect is investigated separately. Then, the sum of the effects is analyzed to predict the improvement of audio quality. Finally, the calculated results are compared with low level simulation in order to confirm the validity of the analysis.