how can i access the door speakers? is it necessary to take the door panel off? where is the "front/rear and left/right division points" for the speakers. this is how the creative wiring is labeled by MB and is important since it looks like two of the speakers are wired in parallel (the triangle and front door; the rear door and the rear deck). i need this info to figure out a difficult problem that i have. would be happy to discuss my situation with those interested. one last comment. it appears to me that an EZ "cheap" way to vastly improve the quality would be by using a high level input amp and leaving everything else alone. a plug could be custom made to connect to the input plug from the HU and from the output plug to the speakers. i would likely disregard the rear door speakers. there are some very decent amps that accept high level input. another option might be to use a line level converter in the trunk, one that is adjustable (mv output)...any comments or advise is very appreciated..

Unless you have the MB cell phone unstalled (which means you need to keep the factory radio) I would replace the the head unit as well. You have a double DIN opening so you can install almost anything you like.

Using an amp with high level in is one solution, however this does NOT lend itself to very good sound quality (for a number of reasons)
Even worse is the line level adaptor. If this is a choice you must make, go for the amp with the line level in (there are several brands)
As for wiring, if you replace the factory head unit, run new wires to the speakers as well. This requires the removal of several peices of the interior, so depending on your level of expertise, you may not want to tackle this.
Also, be sure that all connections are soldered. Don't let anyone try to get away with any of those colored butt connectors.

Good luck.