Say your head unit's voltage out is higher than the input sensitivity on your amp can go. Should you get a line driver to match the amp's highest sensitivity, just max out the gain on the amp, or what? I hadn't thought about that as an option before. The headunit voltage is 4V and the amp I'm getting is 5V max input sensitivity, but I am getting one of the Eclipse 8454's which have the 8V outs. Anyone's thoughts on how that whole thing works is appreciated.
you'll actualy have the input sensitivity minimized to reduce the input stage of the amp's sensitivity to the high viltage signal. Give it a try and see how it works. This is an AC voltage we're talking about, so these really are RMS values. It may not cause any problems.