Preventing pop noise in TV sound

In order to quickly decrease the voltage applied to a mute pin 18 of an audio amplifier circuit 19 of an electronic appliance, an end of a capacitor 20 connected to the mute pin is connected to a discharge circuit which is switched on, when the appliance is switched from on to off or stand-by, by exploiting two power supply sources 35, 36 of the appliance. The voltage output of one power source, e.g. fly-back transformer 36, decreases faster than the other power source, e.g. switched mode transformer 35, when the electronic appliance is switched off. An active element 27 of the discharge circuit has an electrode coupled to the first source and another electrode coupled to the second source so that the active element is switched on as soon as the difference between the two output voltages reaches a threshold.