An audio receiver includes a first signal port, a second signal port, a power supply port, a power ground port, and an amplifier circuit. The first signal port is coupled to an audio signal line of a transmission interface. The second signal port is coupled to an audio ground line of the transmission interface. The power supply port is coupled to a power supply line of the transmission interface to generate a power supply level to the power supply line. The power ground port is connected to the ground level and to a power ground line of the transmission interface. When the audio receiver is outputting a power supply current to the audio source device through the power supply port via the power supply line, a connection state between the second signal port and the power ground port is at a high impedance state.