25. When the volume knob is between the OFF and 9 o'clock positions, the K7 will have no output. Is it normal?

If the volume knob is between the OFF and 9 o'clock positions, the K7 will have no output. This is a normal feature of the analog potentiometer, since it is designed with a certain space in the initial and final sections, which is reserved to accommodate errors. The system will debug and monitor the reserved space, so it will not affect normal uses.