How to Hook Up 2 Amps With 1 Power Wire: Step by Step

We occasionally receive e-mails and comments from inexperienced automotive audio aficionados who enjoy rocking out – incredibly loud and hard. “How to hook up 2 amps with 1 power wire?” a recent one inquired.

This may appear perplexing at first, but it’s actually not that difficult. I mean, it’s not much different from adding a single amplifier.

It is possible to wire two amplifiers, or even numerous amplifiers, in a single automotive audio system, but it requires additional effort, time, and, most importantly, preparation.

Is It Possible to Have Many Amps in a Single Car Audio System?

Absolutely. As long as you connect them properly, you may install any number or combination of amplifiers in a car audio setup. However, your electrical system must be capable of handling the load.

If you add too many amps and they consume too much power, you may need to upgrade your standard electrical system. Flickering or fading headlights is one of the most prevalent signs of an amplifier overwhelming the alternator. This occurs because your amp(s) are starving them, leaving you with two options: lower your sound system or update your charging system.

Whether you should utilize numerous amps or one multi-channel amp to drive your speakers relies on a number of things, including what you’re trying to achieve, your personal preferences, the amount of available space in your car, and, most significantly, your money.

The most typical purpose for wiring up several amps is to have one multi-channel amp powering your main speakers and a second mono channel amp powering your subwoofer.

If you decide to go with numerous amps, the technique of multi-amp wiring is identical to that of single amp installations. You have a couple of possibilities, but it’s critical that you consider the increased current draw.

How to Hook up 2 Amps With 1 Power Wire?

As previously said, whether you’re wiring one or more amplifiers, there are three critical factors to consider:

  • The power cable
  • Grounding wire
  • Turn on wire using a remote

We’ll go through each of these cables in detail below to show you how to connect them when installing a second amplifier in your automobile.

How to Run the Power Wire?

You have two options when it comes to amp power wire: run separate power cables for each amplifier or run a single connection that feeds them all. One of these options may be the best option for you, depending on your situation.

The best and most beautiful way to do it is to use a single power cord. If you pick this option, ensure sure your power connection is thick enough to accommodate your amplifiers’ higher electrical current requirements; otherwise, the amplifiers will not operate properly or output their rated power.

To put it another way, your power cable must be much larger in gauge than the suggested gauge for each of your amps since it must support the current draw from all of them at the same time. For example, if your amplifiers require 8 gauge wire, it’s strongly advised that you utilize 4 gauge cable for your run to the battery to guarantee appropriate current flow. The greater the gauge wire you select, the more demanding the audio system will be.

A power distribution block is the finest – and cleanest – method to connect many amplifiers to a single power connection. The latter is a cost-effective and practical method of spreading an electrical circuit from a single input source to several branch circuit devices.
Not only would using a distribution block save you the trouble of passing several power cables through the firewall, but it will also result in a cleaner installation.

A distribution block may also be fused, which is useful when amplifiers aren’t equipped with built-in fuses.

How to Run the Ground Wire?

Use a ground distribution block to connect the grounds of all your amplifiers to a single connecting point to eliminate ground loop difficulties and noise.

Each of your amplifiers should be linked to the ground distribution block, which should be attached to a suitable chassis or subframe ground, ideally within eighteen inches of the amplifiers’ placement, and should be a mirror duplication of the power distribution block.

It should be noted that the ground wires on your amps must be the same precise size as the car audio power wires. Furthermore, the cable that connects the ground distribution block to the grounding point must be the same size as the cable that connects the battery to the power distribution block. This is done to guarantee that current flows smoothly and properly.

How to Run the Remote Turn-on Wire?

A blue cable on the rear of the headunit controls the remote. Its major purpose is to “inform” your amplifier when the head unit is turned on. Your amplifier will not turn on if the remote switch-on signal is not there.

A automobile amplifier may be turned on in a variety of ways without the need of a remote control. However, the ideal method is to use the turn on wire from the head unit. However, a remote turn-on signal may not always be strong enough to turn on multiple amps at the same time. Connecting the turn-on leads from your amps to a relay that is activated by your head unit is an excellent way to get around this problem. Using a 12v relay to switch on numerous independent amps at the same time is a very efficient method.

A relay is a type of electromagnetic switch that employs a tiny electric current to activate a larger one. To put it another way, it transforms minor electrical inputs into greater currents.

Rather of getting power from the head unit, the relay in this situation should be linked to another source of battery voltage, such as the fuse box or the battery directly. This effectively isolates the head unit’s turn-on signal from your amplifiers, allowing your amps to turn on and hopefully avoiding current overload issues.

What Should You Do with the Speaker Wires?

Attaching the head unit to your amplifier is the final step in connecting numerous amplifiers to a single source. This is determined by the outputs of your head unit. If your head unit has several preamp outputs, you may connect each set of outputs to a different amp.

If your head unit lacks various preamp outputs, you’ll need to check your amplifiers. Some amplifiers have an RCA pass-through circuit, allowing you to connect numerous amplifiers together. This circuit permits a signal from a source component to pass through an intermediary component without being altered. In this instance, you can connect your first amplifier’s pass-through outputs to the preamp inputs of your second amplifier.

If neither the head unit nor the amplifiers offer multiple preamp outputs, you’ll need to utilize Y adapters to split the signal across your amplifiers.

If your head unit has no preamp output, you’ll need either amplifiers with speaker-level inputs or a line output converter to transform the speaker-level output signal (high-level amplified signal) into an RCA preamplified signal (low level signal).


This is a guide on how to hook up 2 amps with 1 power wire. The best way to do this is to use a switch box and wire directly into the back of the head unit. This will allow you to have a separate amp in the passenger seat and another one in the back of the truck. You can use a switch box in the center console or the glovebox and wire directly to the back of the head unit.