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How to Install Two Amplifiers in a Car?

If you’re looking to improve your car’s sound system, one of the best ways to do it is by installing two amplifiers. This will allow you to connect multiple speakers, fine-tune settings, and get the best sound quality possible.

But to install two amplifiers in a car, you’ll need to have the right tools and understand the various options and factors that can affect your setup. So, how to install two amplifiers in the car? Let’s find out.

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Two amplifiers can be connected in the car as long as the wiring is done correctly. Installing two amplifiers in a car typically involves connecting one amplifier to the speakers and then wiring a second amplifier to the subwoofer.

When it comes to connecting two amplifiers, there are several factors that you will need to consider. These include speakers’ impedance, power requirements, and amplifier classes.

As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.

Tip: Installing two amps in the car often requires running new wiring, adding stronger fuses, or even a new distribution block (links to Amazon).

There are also different ways of connecting both amps depending on the car audio system design: 

Using a selector switch

Using an active crossover

Using preamp output

Using a power wire

In the article below, I will take a closer look at various options and discuss the pros and cons of connecting two amplifiers in the car.

Do You Need Two Amps in a Car?

If you have a basic car stereo system, then the chances are that you won’t need two amplifiers.

In most cases, a single amplifier will be enough to power your speakers and produce good sound quality.

However, installing two amplifiers can make a big difference if you have a more sophisticated audio system with multiple speakers.

Using two separate amplifiers allows you to connect specific speakers to a dedicated amplifier and better control and fine-tune your sound system.

Furthermore, if you have a powerful subwoofer that requires more power than your car’s stereo can provide, installing an additional amplifier specifically for the subwoofer can help improve its performance.

How Do You Hook Up Two Amps With One Pre-out?

Installing preamp outputs is the best method if you’d like to use two amps simultaneously. You’ll use an RCA wire cable.

Here’s the right procedure for connecting two amps with one pre-out: 

Step 1.

Look for the preamp output on your receiver or head unit. It’s typically labeled as “Pre-Out.” 

Step 2.

Get an RCA speaker cable from the R pre-out. Connect it to the R input of the first amplifier. Alternatively, you can use the L pre-out. 

Step 3.

Get another RCA speaker cable from the R pre-out. Connect it to the R input of your second amplifier. Also, you can use the L pre-out. 

Step 4.

Connect your amps to the speakers. 

Step 5.

Test the sound quality

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How Do I Run Two Amps on One RCA Cable?

To run amps on an RCA cable, you’ll have to split your RCA cable and connect it to your two amps. RCA cables come in handy to connect different electrical gadgets. 

How Do I Split My RCA for Multiple Amps?

Here are the three methods to split RCA cables: 

Let’s discuss them in detail: 

RCA Splitter Cables:

  • Get a 2-in-1 RCA cable
  • Configure your device with single RCA output
  • Remove the white and male plugs
  • Plug the RCA splitter cable where you removed the two plugs above
  • You’ll have two pairs of the plugs to insert into your amp

Line Output Converter:

Go for Line Output Converter to boost the number of RCA jacks. It’s the best method if your system doesn’t come with a jack.

Here’s the procedure:

  • Get the LOC to tweak the high voltage to RCA signals
  • Connect the LOC to the output of the head unit
  • The output of your LOC becomes the RCA jack.

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Daisy Chain Connection:

  • Set up your device with one single RCA jack
  • Configure your amps.
  • Unplug all connections
  • Connect your Daisy chain splitter to the RCA jack
  • Plug the wire from the splitter to the input outlet of the first amp
  • Plug the other wire to the output outlet of the first amp
  • Connect the plug from the second wire to the second amp

Can Two Amps Share the Same Ground?

Two car amps can share the same ground, provided you evade the ground loop. It doesn’t matter if you ground them to a similar or different spot or take advantage of an unfused distribution block.

Ensure that the point in the chassis you chose to make the ground is bare metal.

Should I Use Two Power Cables for Two Amps?

It’s better to use two cables and two fuses for two amps due to the high current levelsIn addition, it helps to eliminate power couple crosstalk between the two amps. 

How to Connect Two Amps to One Power Wire?

You can connect the two amps to one power line, especially if you have a few power sockets. You’ll use a distribution power block that distributes the current to several devices.

Here’s how to connect two amps to one power wire:

  • Use a power cable to connect your power distribution block to the power outlet.
  • Get the power cable of one amplifier and connect it to the power output on your power distribution block.
  • Pick the power cable of the second amplifier and connect it to the output of your distribution block.
  • Check the connection
  • Turn on the switch on the power outlet.
  • Turn on your amps

How to Split Remote Wire for Two Amps?

Splitting remote wire is an easy task and is no different from splitting any other wire type.

  • First, cut the tip of your remote wire before you get to the amp.
  • Next, get the wires from your amps.

Also, you can use a jumper wire. Channel it from the remote terminal of one of your amps to the remote terminal of the other amp. 

Can You Connect Two Amps to One Sub?

Connecting two amps to one subwoofer is possible, but to do it right, you should have two identical amplifiers.

Also, you can connect two amps only to the dual voice coil (DVC) subwoofer. This connection type will not work with a single voice coil (SVC) woofer.

How Do You Bridge Two Amps Together?

You need bridgeable ampsHere are the requirements: 

  • One of your amps will have an inverting switch
  • The amps should have a common ground.
  • Your amps should have a more current drive.

Beware that bridging two amps together is hard. You risk causing heat and shocks. 

Can Two Amps Share the Same Fuse?

Two amplifiers can share the same main fuse, provided the fuse can handle the power.

I recommend using a distribution block instead of running the amps on a series connection.

What Size of Fuse Do I Need for Two Amps?

It varies depending on the number of amps you want to wireIf the amps come with an internal fuse, you’ll have to pick a large fuse. Add the numbers to know the correct fuse size for your two amps.

For example, if the amplifiers come with a 20 amp fuse each, the main fuse should be at least 45 amp.

If your amps don’t come with internal fuses, you’ll have to check their power ratings. 

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How to Wire Two Amps Without a Distribution Block?

The other alternatives to wire two amps without a distribution block are selector switch and active crossovers. Let’s discuss them one by one. 

Using a Selector Switch

You can use a connector switch to connect two amps to one speaker or more. However, you won’t use the two amps simultaneously.

You’ll have to buy a selector switch. Here are the steps to connect your two amps with the selector switch:

Step 1.

Go to the back panel and look for “input” and “output” connectors. Use the “input” ones to link two or more amplifiers together. On the other hand, the “output” connects with the speakers. 

Step 2.

Look for the speaker wire from the amplifier side. Connect it to the “A” input. Repeat the same for the R and L output. The R output should go to the R input.

You risk damaging your amps and speakers if you make a wrong connection. 

Step 3.

It’s time to connect the second amp. First, look for the speaker wire of the second amp output and fix it into the “B” switch input. 

Step 4.

Look for the speaker wire of your switch. Connect it to the speaker input. Assuming you have two speakers, connect the speaker wire from the switch’s output to the second speaker’s input.

Step 5.

Your amps and speakers are well-connected now. Use the selector switch to choose the amp to use at the moment.

Tip: Using a selector switch enables you to test the quality of the sound when you change the amps.

Remember to choose a selector switch that will make you switch from one amp to the other seamlessly without damaging both amps.

Using Active Crossovers

Active crossovers come in handy for distinguishing sound frequencies. Here’s how it does it: 

  • High frequencies flow to the tweeters
  • Midrange frequencies are channeled to the midrange speakers.
  • Low frequencies to the subwoofer. 

You’ll have to connect one amp to the low-frequency speakers and the other to the high-frequency speakers.

Here’s how to connect the amps using an active crossover: 

Step 1.

Pick the head unit’s output and connect it to the input of your active crossover. The R head unit should be connected to the R crossover input. Repeat the same process with L channels from the head unit. 

Step 2.

Look for the high output signal of your active crossover and connect it to your amp. Ideally, you want to choose the amp to connect to your tweeters. 

Step 3.

Get the low signal output of your active crossover and connect it to your amp. You’ll pair it with the low-frequency speaker. 

Step 4.

Test how the amps work. Play some music and adjust it with the control knob.

I recommend using active crossovers if you want to enjoy the high-quality sound when you increase the volume.

Can I Use Two Amps for the Same Speaker Set?

You can’t connect two amps to a single set of speakers. If you do so, your amps might blow, you’ll spoil your fuses, or the amp might get into the protection mode.

But if your speakers come with a firewire terminal, you can try removing the jumpers and connecting the amps to the terminals.

However, you’ll need a level control to make the amps produce the same power output.

Also, you have to have identical amps. You can make one amp running only the left channel and the other running the right channel.

What Do You Do if the Amps and Speakers Don’t Work?

It happens. You connect everything well, but you get no sound when you power on your amps.

Follow these troubleshooting prompts if you experience any problems: 

  • Check that the main components are on and plugged into the right spots. Check the volume control knob. Confirm that the amps light up.
  • Check the current settings on your amps.
  • Counter Check your cables from the speaker wire to the amps. Check if the connection is secure.
  • Inspect all fuses. The connections in the circuit can turn off your amp. You won’t hear any sounds. If you encounter any problem, turn off the power supply, then leave your amps to rest for a moment.
  • Don’t stop testing. Test with different cables. Test with another amp.

Test with different connections to see if your amps will work well. 


You can install two amps in a car. It allows you to fine-tune the settings and enjoy listening to different music genres.

Follow the procedures I’ve highlighted above and choose the easiest method that fits your needs.