constant static in speakers

The problem is that even with the radio off or at 0 volume there is low level static coming through. Does NOT whine with the alternator.

Data:

2015 S.CREW, V8 (5.0L), XLT, No Sony, 7 speaker, no NAV, 8" screen.

Aftermarket system:

Hertz Hi-Energy Components Up front
Hertz Hi-Energy Coax rears
JL Stealthbox with 13.5" TW3
Kicker IQ Amp 1000.5
Stock HU

This was installed by a reputable shop. I have been through countless sound systems so I know a fair bit about them.

What I have tested: I took out the signal wires and the static goes away (amplifier OK). I ran completely separate power from the battery to the amp and the sound remained (power wire not bleeding into signal wire). Jumped my remote wire from the constant power in the rear and the sound remained (remotre wire not acting like antenna). Ground is about 3ft long directly to the frame with the paint scraped off. This leads me to think that the problem is in the HU that it is always giving out voltage for some reason. The shop said they had seen this in Fords and other vehicles. It seems really strange to me. Having spent most of my working day scouring the internet for other problems similar to this, I have only seen one or two postings that have come up with the same conclusions. Others have found bad grounds or something else wrong. What do you guys think? I am missing something? Time to throw in the towel and get a noise filter or something?

If you turn all 3 gain controls of the amplifier does the noise go away?

Yes it does. What does that mean?

That means your gain controls are working. Turn them up one at a time till you hear the noise. Then back it down till it goes away. Repeat for the other 2 controls.

Gotcha, so that means that the HU is putting out some voltage all the time, that must be attenuated by the amp?

It means you were experiencing system noise. I have no idea if the noise is coming from the radio or from the amplifier itself. But lucky for you this is why they put a gain control on amplifiers.

Keep in mind that current flows in a circular pattern following the shortest path to ground. Make sure that your systems are not connected to any sort of motor (which you mentioned) or induction devices such as your ignition coils – it’s best that the stereo system has its own fusible circuit. Many shops will use a fuse tap or a wire splice without knowing what circuit they are tapping into. The HU and Speakers were probably connected to the stock connections. Question, how was the JL Stealthbox with 13.5" TW3 wired up – I am assuming that this unit did not have a stock wiring connector? Start there. Also make sure that all the grounds in the stereo system have their own common ground. Another wards, make sure that they do not share another system that has a motor or an induction unit. Good luck, hope you find the problem.

Thanks for the feedback everyone. What do you mean how was the TW3 wired? It did have connector on the box if that's what you mean. WRT the common ground question, I have no idea where the HU is grounded, is there a way to check? I am assuming it comes from the factory grounded to chassis. The ground for the amplifier is connected directly to the chassis for sure, I can see it. I also pulled the RCA's out of the amplifier and the noise goes away, so it does seem to be coming from proximal to the amp. I guess it still could be a difference in ground (reference) between the amp and the HU.

Did the vehicle came with a factory TW3 unit installed. If so, then then the installer would have used the OEM connector.From what you described it sounds like you are getting noise from some sort of coil. I am thinking   that your sound system was wired into a circuit with some sort of induction unit. For example, if you look at wiring diagrams of an engine compartment, there is always some sort of Noise Capacitor for the ignition coils. Voltage is constantly going through the windings (your humming). That’s why a stereo system should have its own circuit. If Ford has a common problem with the noise, then maybe it is a factory wiring fault.

I noticed you are using the stock HU. How is the amplifier getting it's remote turn on power?
If this is a constant "on" connection into the fuse box, than I believe that this is where the problem stems from. Although the HU may be off, the amp is still turned on, but not getting signal from the HU, just it's own static, from caps discharging.
Is the amplifier chassis making a connection to the vehicle chassis, even by the screws used to bolt it down? (Ground loop)