I'm looking at replacing the factory radio with a head unit that is satellite radio ready.

First, could someone confirm for me that the factory radio in the 2005 Limited Coupe is NOT satellite ready?

Second, I went on Crutchfield.com and narrowed (from the 100+) it said would fit my Crossfire to 11 choices. I then did the side by side compare. One of the only differences among them seems to be the preamp voltage (some are 2.0, some 2.2, some 2.5, and a few are 4.0). Someone told me that 4.0 is better but that it can overheat the car. Any truth to that concern? What voltage would you get if you were me? - there's not a huge price difference between them. How much does the voltage affect the sound quality?

 

If your going to use the amp already in the car you will be hooking up to the speaker outputs of the head unit anyway so the pre out voltage will not make any difference. If your going to install an amp then go for the highest volt output.

 

Pre amp voltage is only an issue if you are looking to do one of the following; drive multiple amplifiers, improve signal to noise ratio, or are using amplifier that require a high voltage input.

Most good amplifiers on the market today require about 250Mv input to reach their rated power. Some companies have even chosen to make their amplifiers more sensitive (at the risk of higher noise levels and as a way of making them louder on display boards when compared to better sounding amplifiers) to the point where you only need 100Mv or less.

So, you might be thinking why is it that companies promote more than what is needed. It is a simple approach really.

In adding an amplifier you will adjust the gains at the amp, in most cases that means applying gain at the end of the signal chain, which in-turn automatically means you are amplifying the original signal+noise. Relatively speaking that would mean the amount of noise at the speaker will be louder.

By making the signal at the source higher, then you wind up applying less gain at the amp and as such the noise level is less.

Other factors related to amplifier performance and how to compare CEA 2006 rated amplifiers is attached.

 

As stated above if you are retaining the factory amp you will not use the preouts at all.
You will hook up the front right and left channel only.