If you are referring to a factory amp, that is half of a matched set on GM and Ford products. When you have one of their radios that uses an amp, it must be used with an amp. Their radios that do not use a separate amp can not be used with an amp. Only Chrysler radios can be used with or without an amp. They are only used for tone conditioning for the shape of the vehicle.
Aftermarket radios have the amplifier built in so you do not use another separate amplifier. Most people bypass an original remote amplifier so they can use the vehicle's original speaker wires. That makes the radio installation go a lot faster when you do not have to tear the interior apart to string new speaker wires.
SPONSORED LINKS
Sunday, May 28th, 2017 AT 8:42 PM