4 power amplifiers push-button select input,2 sets of stereo speakers .push-button select output (2 sets of speakers can be opened or closed independently). Sets of stereo speakers can sound at the same time, you can also turn off group of speakers or more groups of speakers individually, manually select the pushbutton . The power of each channel is 300W. input provides vacuum tube power amplifier no-load function. Manual selection of input and output switching, straight plug straight use, switching stability, between channels will not produce another dry close or noise.