PURPOSE: To suppress a level of a pop noise signal at interruption of power and to eliminate the pop noise by supplying power of a power supply circuit supplying power to various circuits of an audio equipment directly to a power line independently so as to supply the power at all times independently of 'ON-OFF' operation of the power supply.

CONSTITUTION: A microprocessor power output circuit 22 is controlled in response to the production of a mute signal at interruption of power and a power supply detection level to a COM/AM/FM power output circuit 23 and a chip enable signal generating circuit 24 is set within a range of a mute signal generating level. Thus, if the mute signal is lost, the power voltage of a car audio equipment 10 is lowered considerably, and then the mute signal level is decreased in matching with the sequential decrease on a voltage level of each power supply and a pop noise at interruption of power is not almost given to a speaker 9.