2. Or add a switch on the front of the car after connecting the long battery, which is also a way.
3. The player itself has a long battery, one is for the key door, the other is the iron wire, and the other is the night light line. You can connect the power amplifier to the player's key door.
4. It is very cumbersome to throw the line from the front of the car to the back of the car. Pay attention to the route of the line and pay attention to the safety of electricity. It is best to find a professional for installation.