I have a f900bt in my car. At the time I never hooked up the radio because the majority of my music was on my phone. I am trying to hookup my headunit to the radio in this car. For the life of me I cant figure it out. In past cars the antenna lead up to the stock headunit. All I had to do was plug it into the back of the aftermarket. With this car, I understand theres an amplified radio signal? Anyways my question is, how do I hook up the radio.