[mistryn]

Originally Posted by makkan00

I think your harness is picking up noise on its way to amp. Check it again especially on passenger side footwell.

Further research leads me to a post by Techinics, see post 4 -
http://www.e90post.com/forums/showthread.php?t=708029

Earler post by another member

You are correct in assuming the passenger side is the noisy side of the
car. Yes you run the power wires directly to the battery for all your aftermarket stuff with a fuse. There is some debate at to how noisy the
chassis grounds are. One of the professional installers on this board suggests
running both the power and ground directly to the battery and since I bought his kit that's what I did and I don't have any noise. People that have used the other grounds have had mixed results. I think you only need to follow the existing wire routes to get good results but I guess is you started out with a base system they might not be there. I think most are buying the Technic Harness and he has a route plan with that. If you look in the Audio Contents
thread there should be some examples

I have attached the ground to one of the bolt holes where the CD changer would sit so may look at another ground point - I did sand it down to bare metal but that might not be a good point.

Also I have ran both looms down the passenger side

The standard layout install of the Stereo harness that I use is attached below...

I normally run the output extension cable under the center console left side, under the driver seat and then door sills towards the trunk via the rear seat. The input extension cable is run the same way but on the right side. At the same time time I run the center and underseat woofers wires.

I am going to pull the HU out tommorow check the connections and if the noise still persits then re route the wiring loom as per in the thread down the centre console by routing the outgoing down one side and the amped cable down the other side of the console

I dont have a phone jack to rca adapter but may pick one up from maplins and try it with my iphone in to the rca jack.