The present disclosure is directed to a device that includes a headphone speaker housing that includes a coil having a first terminal and a second terminal that is configured to operate in a sound generation mode and a battery charging mode. A class D amplifier circuit is configured to rectify in a battery charging mode and amplify in a sound generation mode, the class D amplifier is coupled to the first terminal and the second terminal of the coil. The class D amplifier including a first, second, third, and fourth switch, the first terminal coupled between the first and second switch, the second terminal coupled between the third and fourth switch. An audio generation circuit having a third terminal and a fourth terminal, the third terminal coupled between the first and third switch of the class D amplifier and the fourth terminal coupled between the second and fourth switch of the class D amplifier. A battery charging circuit coupled to the third terminal and the fourth terminal.