1. The noise of the switch is small and will not have too much impact on the speaker. It is recommended to add a horn protection circuit. The horn protection circuit can not only eliminate the impact noise of the amplifier switch machine, but also avoid the output DC burning the horn when the amplifier is damaged.2. The bottom noise is small. floating small, do not need to do any debugging after installation, the output drift voltage will generally not exceed 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,but in good condition.2.The PCB board has change to black, but the function is .Operating voltage: Dual DC 10 - 45V recommended Dual DC 35VRated output : 100W(4 Ohm 35V)Maximum output : 150W (4 Ohm 45V) enormous heat, is not recommendedPCB size: 30 x 50 x 35mmPitch: 5.08mmHole distance between two tube: 47mmcolor:As shownMaterial:PCBPackage Contents:1 x Amplifier boardOnly the above package content, other products are not included.Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.