What is the voltage of the rem wire on a car amp?

The rem (remote) wire on a car amplifier typically carries a voltage of around 12 volts. This wire is used to turn the amplifier on and off, sending a signal from the head unit (stereo) to activate the amp when the car is turned on. When the ignition is in the "on" or "accessory" position, the rem wire should receive a voltage close to the battery voltage, usually around 12-14 volts.