It wont matter as far as the amount of signal. What they are doing is preventing any noise from entering the system down the line, and amplifying that as well. By putting it in the front, you have your strong signal and noise really doesnt have a chance to enter in the RCAs, and even if it does the signal to noise ratio is much better than you had before. You can boost the signal up front, down the line, and then back it off at the amp. That way your amp is receiving a strong signal already, you dont have to crank your amp's gain up to get the same volume at the speakers, plus the noise from your car wont be heard (or shouldnt be heard anyways).
-There are 10 kinds of people. Those who understand binary, and those who do not.
-If we ever forget that we are One Nation Under God, then we will be a nation gone under...Ronald Reagan