Features: 500W power amplifier board, the input signal sensitivity is 1.5V rms, if the input signal voltage can't reach this value, recommended to add a preamplifier. HiFi amplifier board can help you amplify the weak signal from the audio source or pre-amplifier without changing the sound quality. Support output short circuit protecting, output direct current bias protecting(speaker protecting) and over temperature protecting, safer to use. Made of high-quality material, it has nice durability, with cooling fan and aluminum alloy heat sink, nice heat dissipation. The rated power supplys voltage is dual power supplys ±65V, and the voltage can work normally at ±58--±70V (over 70V, it will burn). Specifications: Material: PCB + Aluminum Alloy Power Supplys Voltage: Dual Direct Current Power Supplys ±58---±70V Rated Output Power: 500W (±65V power supplys 4 ohm load, distortion 10%) Efficiency: ≥90% Signal to Noise Ratio: 90dB Frequency Response Ranges: 20Hz-20KHz Speaker: 4-8Ω Voltage Magnification: 36 times Input Sensitivity: 1.5V (RMS) Output Short Circuit Protecting: Yes Output Direct Current Bias Protecting, Namely Speaker Protecting: Yes Over-Temperature Protecting: Yes, the radiator field effect tube temperature is higher than 100 °C, turn off the output! Item Size: 98 * 43 * 30mm/ 3.9 * 1.7 * 1.2in Item Weight: 95g/ 3.4oz Package Size: 100 * 50 * 30mm/ 3.9 * 2.0 * 1.2in Package Weight: 100g/ 3.5oz Packing List: 1 * Power Amplifier Board