can you eliminate audio whine?

The car is a 2006 MINI Cooper. I have the following audio set-up. JL Audio Components (up front) JL Audio HD 900/5 JL Audio stealth box w/subwoofer Pioneer AVIC -N3 I have my car in a shop right now and they are saying that the MINI (BMWs) are prone to some audio whine. As demonstrated by the installer (using a stethoscope like devise), all speakers and amp (JL audio) were disconnected from the head unit. No power to the amp, but the power cable was still connected. The installer checked all power cables, rca's, etc. and showed me that everything is installed correctly (proper grounding, etc.). The installer even tested a different head unit and the whine is still there. So, we ruled out the existing head unit (Pioneer). What we discovered is there is still a slight whine coming from under the battery compartment. The whine gets amplified after powering up the amp, but can be dialed out of the speakers using gain control. However, the whine still remains present even though it's not coming through the speakers. Any thoughts or suggestions are greatly appreciated.

If it is not coming from the speakers, I can not help you.

The easiest way is to try gruond loop isolators. Im sure there is some one her who can tell you how to eliminate the whine without them but it's what I have used in the past.

Is this car supercharged?  We had a mini and with everything off except the engine we could hear a wine/somewhat whistling noise but it was definitely coming from the engine.  The customer believed it was our installation but when we showed him everything was off and it was not coming through the speakers it finally convinced him it was under the hood, not in the car.Advanced

BTW, the stethoscope device was used to isolate the location of the whine. Which is how we determined it was coming from under the battery. Definitely not coming from the engine. The battery is located in the rear of the car (center) for a MINI. The installer has tried ground loop isolators, said he rarely if ever has to use them. He even ran high quality RCA's (twisted and shielded), and all cables are on the opposite side of the battery power lead going to the front of the car. The installer even tried running the RCA's outside the car to see if was interfering with other OEM wires. So, we've ruled out the RCA's.

Yes, my MINI is supercharged.

i am an idiot wrote: If it is not coming from the speakers, I can not help you.

With everything connected, the whine will come through the speakers at a slightly higher volume (which would make since if the amp is not the source). The whine will slightly increase with revving the engine, but not by much. The goal is to eliminate the whine all together. So, we tracked down the source as described above. Thanks in advance for your help.

If you turn the gains of all amps all the way down, do you hear any whine coming from any speaker?

If we adjust the gains all the way down, the whine is almost completely gone. Still there, but very slight.

One thing I forgot to mention; My car was recently in for service for a radiator fan replacement. When I got the car back, the whine noise was gone. At first I thought, nahhh can't be! The stereo was off, as the service required disconnecting the battery. Since it was off, I never turned it on. The whine was completely gone. Got home, turned the car off. Went back out later to drive into the city and no whine. Again, I had not turned on the radio. I was enjoying the whine free ride. As you might expect, the second I turned on the radio, the whine slowly came back. This is the reason why I having the installers take a second take at eliminating the whine. It's got to be in the stereo wiring or grounding, but it's definitely not related to the MINI.