how do I connect an amp to a standard head unit?

[teejayy]

yaris2010RS, if you gave me your Amplifier's name I could answer this more accurately.

Essentially a Line Output Converter converts high-voltage speaker-level signals from your Head Unit down to an acceptable pre-amp level signal ideal for Amplifiers. You then connect the Line Output Converter to an appropriate Amplifier using RCA patch cables. If you purchase a Line Output Converter with a remote trigger, which is advisable, it will turn on your Amplifier when it detects an output on your factory speaker wires.

Of course if your Amplifier has built in Speaker-Level Imputs (can be called High-Level Imputs) you can use these instead of going down the Line Output Conveter route. Essentially the Amplifier has built-in circuitry which uses the Low Impedance, High-Level Output from factory speaker wire as an Imput. The Amplifier uses signal sensing so when the Head Unit is turned on and an audio signal is on the speaker wire, the Amplifier "sees" the audio signal and turns on, eliminating the need for a separate remote lead from the head unit.

If your Amplifier doesn't have Speaker-Level Imputs then a Line Output Converter is an ideal solution. There are many Line Output Converters on the market, Crutchfield sell a Scosche SLC4 which is an ideal solution if your are aiming to use a multi channel amplifier. I have also heard good things about David Navone products, and I know that some of his products do include Remote Triggers.

Once you've got the Amplifier working off the standard Head Unit, the rest of the install is a piece of cake!

If you feel that information is not accurate please do correct me, but I have answered this to the best of my ability.

Good Luck with the install!