Features： 1.LOW NOISE: The noise of the switch is small and will not have too much impact on the speaker. The background noise is very small, ear close to the speaker basically can not hear the noise. 2.SPEAKER PROTECTION CIRCUIT: Speaker protection circuit can not only eliminate the amplifier shutdown impact noise, but also when the amplifier is damaged, to avoid the output DC burned speakers. (Recommended to add) 3.STABLE TO USE: Amplifier board installed without any debugging, the output 0 drift voltage generally does not exceed 50mv, and more stable. 4.DURABLE AND RELIABLE: Because of the use of the classic circuit, stable and reliable work, the production of some misuse will not necessarily damage the components, there is a certain degree of durability, the production success rate is high. 5.NO DEBUGGING: As long as you are installed correctly, no human error, basically a success, without any debugging, beginners also have a very high success rate. specification：Item Type: Amplifier Board Material: PCB Operating Voltage: ±10 to ±45V (Recommended Voltage (+35V)?0?(?35V)) Rated Output Power: 100Wx1(4Ω±35V) Maximum Output Power: 150Wx1(4Ω±45V) Input and Output Seat Spacing: Approx. 5.08mm/0.2in Hole Distance Between Two Tubes: Approx. 47mm/1.9in Power Tubes On The Board: 2SC5200 and 2SA1943 (Disassembled) PackageList：1 x AmplifierBoard Note：All data are measured manually, and there are certain errors in the measurement results.