You must know this famous saying, seeing is believing, but hearing is empty, but in the field of sound, he does the opposite, that is, seeing is believing and hearing is empty. Many domestic power amplifiers are deceptive. For many upstarts who get rich overnight and have no education, they have been cheated and don't know what happened. Finally, they want to say thank you. It's really ridiculous. The way to judge is that, on the surface, the input interface of the backplane is 5. 1 and the output interface is 5. 1 channel amplifier. This is only what you can see on the surface. The stereo is for listening, not a vase for decoration. If you listen to it, it will show its true colors. It is ok to have a real CD with 5. 1 channel at hand, or a movie. There are also products produced by large companies that are guaranteed and can be purchased with confidence.