USB is digital audio and TV is analog audio output. Your TV has no audio digital-to-analog conversion output switching ability, so when playing USB, the TV has sound, and there is no audio conversion and no audio output to the power amplifier. Watching TV and watching video TV can output audio signals to the stereo normally.
Cause: Check the input audio signal to see if it is not inserted correctly. There is something wrong with the audio cable. Try another cable. There is something wrong with the power amplifier integrated circuit. Check the speaker cable. Features small size, easy to carry, cool appearance, trendy fashion, personalized color matching, fresh and natural.
If the TV has an earphone socket, you can also use an audio cable to directly connect the power amplifier audio through the earphone socket. But there is no sound when the speakers on the TV are connected. A decoder for converting digital/optical fiber into ordinary analog audio output was purchased online, and it was connected through the digital coaxial interface on TV.