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How to Hook Up 2 Amps with 1 Power Wire

Having a single aftermarket amplifier is sufficient for most car owners.

For example, if you’ve got a 5-channel amp, it’s good enough for a 4-speaker system + a regular subwoofer.

But what if you want to have multiple subwoofers?

Well, in that case, you’ll have to install two amps in your car first.

Can You Install Multiple Amps in Your Vehicle?

Yes, there’s no limit regarding how many amplifiers you can install in a vehicle.

But still, you have to consider your vehicle’s electrical system before making any amp upgrade. Installing multiple amps in a vehicle can put a heavy load on your electrical system, and you may experience a voltage drop.

Therefore, upgrade your battery, alternator, and big 3 wires (you can add a car audio capacitor too) before adding an extra amplifier.

How to Hook Up 2 Amps with 1 Power Wire

Installing two amps in a vehicle is similar to how we typically install a single amp.

It means finding the optimal location for the amps before anything else. It should be airy, clean, and dry.

After that, you’ll disconnect the negative terminal of the battery.

Then we’ll install an in-line fuse on the power wire and run it from the positive battery terminal to the amp. Since we’re dealing with two amps, we’ll use a distribution block (one input, two outputs) to convert this single power wire into two smaller wires.

The main power wire will run from the battery to the distribution block input. Then we’ll connect one end of these smaller wires to the distribution block outputs and the other to the amplifiers’ 12V terminals.

Other Wires

Apart from the power wire, there are some wires that you need to tweak when installing an extra amp.

Ground Wire

 Like the power wire, we’ll use a distribution block to make two ground wires out of a single one. The main ground wire will be connected to the grounding point on one end and the distribution block input on the other. Then we’ll connect the distribution block outputs to the amps using two smaller ground wires.

RCA Wire

The RCA cable carries the preamp audio signal from the head unit to the amplifier.

The number of RCA cables you’ll need will depend on your head unit. If your head unit has multiple RCA outputs, you just need to connect them to your amps.

But if your head unit has only a single RCA output, you should check for RCA pass-throughs on your amp

If your amp has no such pass-through, you’ll need a 1-to-2 RCA distribution block. It will work exactly like ground and power wire distribution blocks and will have one input and two outputs. You can then connect the output RCA cables to the amplifiers.

If you’re short on budget, you can use a Y-splitter instead.

Remote Turn-On Wire

The last thing we need to deal with is the remote turn-on wire.

This wire signals an amp to turn on whenever we turn on our head unit.

When we install a single amplifier, we need to send a 12V signal to turn it on or off because the amp would always remain turned on and drain our battery. That’s why we use a remote turn-on wire that runs from the head unit to the amplifier.

But since we’re installing two amplifiers here, some mechanics recommend using a relay that turns on the amps one by one. But there’s no need for that. Instead, you should run one remote wire from the head unit to the amp. Then run another wire from the remote input of the first amp to that of the second.

Now you can turn on both amps without any added complexity.

Michael Brown is the founder of, a website that provides car audio installation guides and tips. A self-taught car audio enthusiast, Michael has been installing and modifying car stereo systems for over 15 years.

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