Hi, I recently got a new jbl amplifier. Previously i have had cheaper amplifiers such as Pyle. Anyways i must say the sound quality is definately better. When i turn my car on its fine however if i have the radio on or turn my car off and dont take the key out (so the radio is still on), and then i turn my car on, there is a thump sound. Basically if you have the radio on the sound appears as soon as the car is turned on. This did not happen with my old amplifiers. Does anyone know why this is? Could it be a faulty amplifier? Thanks.