I'm hearing this low whinning noise coming from my engine through my speakers after installing my new sound system. After doing some research in the forum, it seems like I might need a ground loop isolator. I kept the factory JBL upgrade headunit w/o the navi, JL audio components in the front, JL audio 3-way 6x9's in the back, JL audio cleansweep, 2 JBL amps, and a JBL subwoofer. The guy who installed it said that he did all he can do to minimize the noise. I trust his work because he was highly recommended by some ppl I know. But I didn't check the grounds from the amps or how he ran all the wires. I only hear this noise between songs. Other than that the sound is great, but it would be nice not to hear this low whinning noise. If I do need ground loop isolators, will I need to buy one for each channel and how do you install one?