Surge current: A sound equipment is composed of components such as resistors, capacitors, inductors, transformers, etc. They are all in a cold state before starting up. When starting up, its resistance value is small, so the instantaneous current is high, which is 2.5-3.5 times the normal working current. This current is called surge current and can cause damage to the circuit. It occurs at the moment of turning on or off, rather than being damaged during normal working conditions.

Reverse peak voltage: Inductors, transformers and other units have a characteristic that when a voltage is added or removed from the circuit, the unit will generate a Counter-electromotive force to prevent the change of the voltage. Then when a voltage is applied to the inductance component during startup, it will generate a Counter-electromotive force to prevent the voltage from being established. However, the power supply voltage is continuously supplied with energy, so this Counter-electromotive force only acts as a voltage damping function, having little impact on the circuit. However, the situation is different when the machine is turned off. When the machine is turned off, a Counter-electromotive force is generated in the circuit without any blocking. This voltage is the back peak voltage, which is 9 times the normal voltage. Although its current is small, the voltage is high, causing an impact on the equipment. So the surge current and back peak voltage of each audio unit simultaneously act on the audio equipment, causing a large impact, which is easy to cause damage to the equipment. In this country, it is best to sequentially turn on and off each audio unit one by one. The correct startup sequence is to follow the direction of the sound source signal flow: turn on the card holder, CD player, LD or VCD player, tuner, equalizer, and finally turn on the power amplifier