Hello Group,

I'm new here, having just bought a low mileage 03 540i 6 speed (37k) and have been researching a stereo upgrade. This is the worst sounding car I've ever owned (may be a bit of an exaggeration but its bad)

I have dsp system with MID in dash

I do not have NAV, cell phone or a cd changer

I have read that once I unplug the dsp amp from the system that I should have 4 channels of 4+V of output from the radio control box

Problem is I don't know where the radio control box is. All I see in the trunk is what looks like the amp itself (a black box about 2x8x12") and plugged into the top of that box are 3 plugs

1 - a 15 pin plug (larger pins then the other two)
2 - a 18 pin plug
3 - a 26 pin plug

I would like to completely eliminate the factory amp and replace it with aftermarket. I would like to add simple Ipod integration

I would also like to upgrade the front door speakers, but do away with the rear door speakers. I will put a coax or some such speaker in the package shelf for rear fill and add a small sub box in the trunk.

My question is can someone walk me through the specifics of the factory wiring I'm seeing in the truck? Is everything I need to tap into right there, or, is that radio control box hiding somewhere else?

I do not want to cut into the wrong stuff and am looking for a very simple system ... good/great soundstage up front with a little rear fill.

I am very confused about what is present at those 3 plugs in the factory amp and would appreciate any / all advice you can give me. Pictures and/or links to previuosly installed systems would be a plus. I have read the old articles but have not seen pictures / descriptions of my later model car. Most of those write-ups seem to be from the late 90's as folks were still learning about the dreaded DSP systems.

(I really expected to see the radio control box back there as a second box which I do not)

Best Regards,

Michael in MD

2003 540i 6-speed
Sterling Gray / Black