07 bmw m5

Installing an alpine vehicle hub, nav tv, 3 amps and componets to stock system, having major engine noise thought it was our equipment but realized it was the car, there engine noise coming from trunk floor board now here is my problem i hook up my equipment to it , it will amplify the noise signal so my question is does anybody know what this noise can be that is causing the engine noise without any new components in the car.

100%guatemalan

Is there a speaker under the floor board?  is this noise also coming through any of the factory speakers as well?  is it alternator whine or another type of noise..(does it increase in frequency as RPM's go up?)

This sounds almost as odd as the issue I am having with an 07 Acrua TL type R...check this one out people..

https://www.the12volt.com/installbay/forum_posts.asp?tid=91118&KW=master5

Perhaps the factory is trying to sabatoge us again?? you think???