Originally Posted by ChrisG
1. After looking at the wiring schematic of the radio it only sends front right and front left signal to the amplifer. Are these leads already under amplification from the headunit?
The head unit gives out a typical signal to the amp using only front channels.
2. As stated above the head unit only sends front sound signals to the amp. Does therefore the headunit recognize (auto voltage sense) that the front is only being used and that is why we don't have a fader or.... Does the headunit really come with a limited circuit that does not have a fader control.
In the harness there is only 4 wires (left +,-, and right +,-) The amplifier does all the crossover points and controls the tweeter, mid range, and sub behind the seat for each chanel. There is no fade as there is only one full range set on either side of where you sit. If you wanted front and rear you would have to install additional speakers somewhere and run the wires for it.
3. Does this car have a factory CD changer option from D/C? If so what input block (i.e. wiring harness input pins) does it use on the back of the headunit.
I haven't physically looked at the amp, but there was no wire run to the back of the car like in the SLK. I know the SLK has the option for a disc changer, but I don't believe it is available for the crossfire. If someone could look at the amplifier they can see if it has a bus cable to run such a thing. 2nd question would be (will the head unit support a changer?)
4. Does the headunit have an aux audio option input? and if so what button on the headunit, controls the choice for the input.
No, but if you look around tech mods section, there is a guy selling a piggy back adapter for such a thing. Found that on a MB board. The only other wire on the harness that wasn't usual was a cell phone mute wire. The amplifier has this option and can be wired in to use it.
Finally, after replacing the factory deck, I noticed the low speed low volume is still in tact. It is controlled by the factory amplifier. No speed sensor wire is run to the actual head unit. Just an FYI.