After rebooting the tone board, the sound is not heard properly so you must always remove the cable and reconnect it to make it sound properly
We need more information to figure out the issue, can you specify more details about the sound problem?
Do you use an external power source?
Can you take a picture and show us the connection bewteen the PC, KTB and the Power adapter?
Did you try to connect the KTB(Khadas Tone Board) to another USB port? Not sure if the USB port with lower output voltage or current.
Can you take a photo to show the connection bewteen the KTB and your PC?