Re: Quick Help Needed With New Head Unit
A 4v pre-out will certainly be quieter than an amplified signal. A signal from a car amp should be approx 12.5v. The problem is that it is also carrying 25-50watts depending on the amp in the head unit. Amplifiers don't like to have large amount's of watts input into them. Normally the signal stage of an amp will only tolerate an amplified signal for a relatively short time before something gives and it blows up. The resistors and capacitors in a signal stage are not normally rated to take the additional strain/heat. It is possible that the stock amps can take the beating of a 25watt 12.5v input, but I doubt it. I would say that it is just a matter of time before it blows up.
Think of it this way, would you ever take the speaker wires coming out of you home theater amp and plug them into the rca inputs of another home theater amp to make it louder.