Plan it out first.

• Decide where you are going to mount the amp(s).
• Decide how much, and what gauge power cable you will need.
• Decide how long your RCA cables will need to be. You should take into account that the cable will be running from the center of the car, out to the side, and around several bends and curves.
• When deciding how much power cable, think about how you will run the cables first! You don’t want to get 18 feet of cable, and then realize you can’t go down the middle of the car, you have to go down the side, and it needed to be 2 feet longer!
• It is often easier to just take out the seats, kick panels, and sill plates before starting. It just makes it easier to work, and often you need to do all that anyway. Removing the front seats is optional, but it gives you more room, easier to lift the carpet, and it is often best to run the wires there. As you remove the seats, take note of where they run close to the floorpan. It's easy to accidentally crush your wiring when bolting the seat down, and that is very frustrating. Once you set your mind to it, it’s really not that hard. A cordless drill and a socket set make it a breeze. I have taken apart many an interior in 10 minutes, and can assemble it again in about 15, if I am in a hurry.

Mount the amp(s).

• Find a good solid, flat surface to mount the amp to. Make sure it’s not in a place that will be hot, or not have proper ventilation. Amps can get hot anyway, and you must help them stay cool, for longer life, and less chance of thermal shutdown. If you want, you can mount a board with vinyl, or carpet on it, for cosmetics, and mount the amp to it. You can also mount your power distribution blocks to this board. Mounting to an amp board also reduces the amps contact with metal, and that helps to prevent "ground loops".

RCA's

• Get a good quality set of RCA cables. Normally, a simple pair of shielded RCA's work fine.

• Connect a remote turn on lead wire to your "power antenna" or "remote" lead from the head unit. Run the RCA cables, and remote lead, from the head unit, down the middle of the car, or down the opposite side of the car from the power cable. The remote lead will serve as a turn-on for your amp(s). This doesn’t have to be very thick wire, 16 gauge is fine. If you have room, you can usually remove the sill plate, and lift the edge of the carpet, and run the cable(s) there, proceeding to the back of the car. Be sure not to put them anywhere they will get crushed by anything. Run all the wires to where the amp will be installed.

Positive Power cable

• Find a spot to go through the firewall. Look for a plug that’s already there. If you find one, you can often make a grommet out of it. If there is none, don’t worry. Just find a place to drill, on the same side as the battery, and install a grommet. Run the cable through the firewall, and up to the battery. Don’t connect it to the battery till you are all done. Most cars will have grommets large enough to use. Don't worry if there already are factory wires in your grommet, just be careful not to damage them as you run the wire through. One helpful method is to get a long thick probe (an old car antenna mast works great for this). Grind the tip to a point, but don't sharpen it.  You can tape your power wire to this probe, and run it through the grommet. If your wire is fairly large compared to the grommet, than you may wish to tape a smaller gauge wire to act as a leader.
• Within 6"-18" of the battery, install an inline fuse. For most systems, a 50 or 60 amp fuse is plenty. If it’s only a small amp 30 or 40 will do. DO NOT skip this fuse! This one is mandatory! It could stop your car from catching on fire in an accident.
• With the wire through the firewall, run the cable to the back of the car, staying on the opposite side of the RCA cables. If you are going to have more than one amp, you want to install a distribution fuse block. Connect the power cable to this fuse block. You then run another cable from the fuse block, to the amps positive (+) terminal.
• Be sure to use split loom tubing to protect your power wire under the hood. This is an IASCA requirement. Also, use loom anywhere a wire runs over a rough metal edge. Use wire ties to keep the wire from being drooped over your engine.

Ground Cable

• This is where most people make mistakes. This is important! First, install a ground cable from the negative post on the battery, to the chassis of the car. If you can reach it, it's best to run it to the firewall, since most cars are a nearly solid sheet of metal from the firewall to the trunk. Make it the same size, or larger than the positive cable. I like to run a 4 gauge or larger to the engine block, AND a 8 gauge or larger to the chassis. Don’t be afraid of over kill here. You spent good money on your amps and the rest of your system. Don’t skimp on a 2 foot length of cable now. I use 0 gauge cable on my own car to the engine block, and 2 gauge to the chassis. Near the firewall, I also sometimes add a piece of 4 gauge from the block, to the firewall.
• Near the amp, install a ground distribution block.
• Find a spot as close as possible to this, to connect a ground cable. You can connect it to an existing bolt, or use a self-tapping screw, or drill, and use a bolt, and nut. If your gonna drill, make sure you don’t drill into your gas tank! The main thing is, wherever you do it, make sure you sand off all the paint, and put it right on the bare metal. You can use some Vaseline here to prevent corrosion, and rust.
• Now connect the cable from the chassis, to the distribution block.
• Run a piece of cable from the distribution block, to the amps negative (-) terminal.

Finishing up

• Connect the RCA cables to the amp(s). Do not connect them before you have grounded your amplifier, and wait till you connect the battery terminal. Often, the biggest mistake people make is to have their RCA's hooked up the first time their amps get a charge. Since the outer shield of the RCA's are grounded, the amp will try to take some of it's ground through them, damaging the preamp of your radio and amplifier.
• Connect your remote lead to the amps remote connection.
• Connect your speaker wires to the amp. (That’s in a different lesson, but the wires should be run at the same time the amp wiring is done.)
• Go back and connect the positive cable to the positive terminal on the battery.
• Now, if your amp(s) have gain controls (and most do nowadays) turn them all the way down to the minimum setting. Now turn it just a hair the other way.
• If you have built-in crossovers, set them the way you will be using them (hi-pass, low-pass, none, etc.….). If they are adjustable, put them approximately where you think will be a good starting point.

Turn the key on

• Turn on your head unit. Put in a good quality CD, or cassette.
• Slowly turn your head unit up to about 80-85% volume. If you hear any distortion, cut it back.
• Go back to the amp(s). SLOWLY raise the gain, and LISTEN for distortion. If you reach a point where the volume is louder then you will listen to, before you hear distortion, then stop there. Otherwise, keep going till you hear distortion, and cut it back slightly till it disappears. Remember that volume setting! That is the max. volume you want to play it at.
• It’s not a good idea to play the head unit at full volume. That’s where most distortion comes in. It may take you a long time to fine tune your amp(s) gains, and crossovers.
• Grab some good CDs (or tapes, if you don’t have CD) and go for a ride. Listen to all types of music, and stop the car, and make adjustments as necessary.
• If you have multiple amps, and an equalizer, it will take much longer to get it set the way you want it. But this is the fun part!