Direct energy conversion of an audio power amplifier represents the total integration of a switching-mode power supply and class D audio power amplifier into one compact stage, achieving high efficiency, high level of integration, low component count, and eventually low cost. This paper presents how self-oscillating modulators can be used with the direct switching-mode audio power amplifier to improve its performance by providing fast hysteretic control with high power supply rejection ratio, open-loop stability, and high bandwidth. Its operation is thoroughly analyzed, and experimental results from a prototype amplifier are presented.