The best way to prevent any damage to your car audio equipment, and monitor the car amplifier voltage is with the DS18 BKVR remote level control with volt meter.
RCA line level control with volt-meter and remote amp trigger can adjust the amplifier gain & turn on/off the amp
In-dash or under-dash mountable
Rotary push turn ON/OFF knob for amplifier remote
Digital volt-meter (10V - 15.9V)
Blue LED display (high voltage/low voltage)
Compatible with most head units & amplifiers combinations
Dimensions: 3.34"x 2.95"x 1.06"