Speaker wire to RCA

Ok...hang on a bit.

First, we need to make sure that we are talking apples and apples. We need to deal strictly with the rca input voltage, not the voltage coming from the battery to the amplifier.

There should be a "gain" or "input sensitivity" on your amplifier (giving the make and model of your amp will help). This should be either a small dial or a hole with a potentiometer near the rca jacks on your amp. This is what adjusts the input on the amplifier to match the output of your LOC. You can use the following method to set your gains. Though it can be effective, it can leave plenty of room for error and incorrect setting. With that caveat in mind:

• Turn the gain on your amp all the way down (counterclock wise).
• Using a well recorded CD, turn your HU volume up until you begin to hear distortion, and then back it off until it is gone. (or turn it up to the loudest point you care to listed to...whichever comes first).
• I would remember this volume setting on your HU and disconnect the mids and highs before doing the next step.
• Turn up the gain on the amplifier (slowly) until you begin to hear distortion from the subwoofer, and then back it off until the distortion is gone.
• Re-connect the mids and highs.

This is very non scientific and some people can hear the distortion better than others. I know of a couple of friends that will turn up their stereo past the point of distortion and think it sounds great just because it is loud. If this is you, I recommend having someone else set your gains. If you feel confident about your hearing abilities, go for it.