1. The noise of the switch is small and will not have too much impact on the speaker. It is recommended to a horn protection circuit. The horn protection circuit can not only eliminate the impact noise of the power amplifier switch machine, also avoid the output DC burning the horn when the power amplifier is damaged. 2. The bottom noise is small. floating small, do not need to do any debugging after installation, the output voltage will generally not 50mv, and is relatively stable. 3. Free debugging. As long as the connection is , is wrong, basically it is a success, no need to do any debugging, beginners also have a very high success rate. Note: 1.2SC5200 + ZSA1943 are disassemble parts, in good condition. 2.The PCB board has change to black, the function is same. Operating voltage: Dual DC 10 - 45V recommended Dual DC 35V Rated output power: 100W(4 Ohm 35V) Maximum output power: 150W (4 Ohm 45V) enormous heat, is not recommended PCB size: 30 x 50 x 35mm Pitch: 5.08mm Hole distance between two power tube: 47mm color: Material:PCB Package Contents: 1 x Amplifier board Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.