Features Made with high quality electronic components, stable and reliable. You can assemble these components by yourself and obtain knowledge about amplifier board. Using military grade double-sided circuit board. Reasonable layout, compact size. 20W Mono Channel HiFi Amplifier Board. Features: 20W Mono Channel HiFi Amplifier Board.Made with high quality electronic components, stable and reliable.Using military grade double-sided circuit board.Reasonable layout, compact size.You can assemble these components by yourself and obtain knowledge about amplifier board.  Specification:Output power: Typical 20W (maximum 30W)Speaker impedance: 4Ω-8ΩTotal harmonic distortion: <0.04%SNR: 105dBFrequency response: 14Hz-100kHz (maximum range 3.29Hz-482.29kHz calculated by RC high and low pass circuit)Supply voltage: Recommended ± 25V (maximum voltage can not exceed ± 30V, 18V AC full bridge rectifier is 25V) Packagelist:1 * Amplifier Board DIY Kit (Require assembly) Package List