How to Hook up 2 Amps with 1 Power Wire

Wiring an aftermarket amplifier to the car audio system is a fairly complex process. It can get even more complicated when you need to hook up two amplifiers using one power wire or to one power source. Adding a second amplifier gives your car audio a major boost, but this is going to depend on what you’re intending to power.

Among the most frequently asked questions by car audio enthusiasts is ‘can you run two amps off one battery?’ Yes. You can connect multiple amplifiers to one source provided that the power signal is strong enough to accommodate multiple amplifiers. Wiring multiple amplifiers to the factory or aftermarket car stereo is not uncommon, but you’ll require extra planning and preparations.

Generally, when wiring the amplifiers, you may want to gather the necessary supplies, including the power wiring, ground wiring, remote turn-on wire , speaker cables, RCA cables, and the inline fuse. You may also want to plan how you’ll utilize the power wire, considering that you’ll require to use one signal to turn on the two amplifiers simultaneously.

Hook up 2 Amps with 1 Power Wire

How to hook up 2 amps with 1 power wire

Much like when wiring a single amplifier to your audio system, it is essential to follow stipulated wiring practices when adding a second amplifier. You may also want to counter-check your wiring diagram to determine which wires to plug into your new amplifier.

Essentially, in order to power the amplifiers, you’ll need to run the main power cable from the amplifiers to the battery terminal to supply them with the ‘juice’ they need to operate efficiently. Although it is not the most efficient solution, using a single power cable translates to less wire clutter and reduced cable-related errors.

Now, because the power wire will be required to carry the current for the two amps simultaneously, you need to get a thicker wire gauge, but this will vary depending on the individual amp’s needs. For example, if you’ve been using an 8 gauge cable to power one amplifier, you may want to double up to a higher gauge (4 gauge and above) to accommodate the power needs of the second amplifier.

Steps for wiring two amplifiers to one power source

I. First off, ensure to disconnect the battery by disconnecting the negative terminal to minimize the risk of electrical shock and shorts.

II. Mount your second amplifier to the desired location, preferably next to the first amp.

III. The easiest way to run two amplifiers off one wire is to get a power distribution block. A power distribution block, just as the name suggests, helps to distribute electrical current from a single power source to multiple devices in the same circuit. The best part about using the power distribution block is that most power blocks come with a fuse, which helps to protect the amps in case of a short circuit.

IV. For this setup, you’ll need to run the main cable (heavy gauge) from the battery to the power distribution block. The distribution block act as a link between the batteries and your two amplifiers. It also provides a platform for running multiple pieces of equipment off the same power source.

V. The next step is hooking up the amplifiers to the distribution block. At this point, you’ll need to use two standard gauge cables to connect each amplifier to the distribution block. Just like any other amp connection, you’ll need to run the cables through the firewall all the way to the amps. If you’re using a grommet to run cables through the firewall, ensure it has enough space to accommodate the extra wire.

VI. You’ll also need to use the power distribution block to make the ground connections. So instead of running separate cables to the ground chassis, use can use the power block to run one ground cable for both amplifiers, as well as for other car audio components. Furthermore, using the power block to facilitate the ground connection has proved helpful in preventing common ground loop problems.

VII. When it comes to connecting the remote turn-on wire, it is not uncommon to use a single lead to trigger both amplifiers. However, considering that using multiple amps will double the amount of current demanded by the amps, using a single remote turn-on wire may not be a viable option.

The best way around this is to get a pair of turn-on leads, one for each amplifier. You’ll then need to add a relay and connect each lead to the relay. Ideally, you can use the head unit to power the relay, but it is recommended to run off the relay of a second battery.

VIII. Wiring your amplifiers to the speakers and subwoofer is going to vary depending on the available preamp outputs. If your factory radio is equipped with multiple preamp outputs, the best way to connect your speakers is by running the speaker wires directly to the amplifier.

The recommended cable sizes are 14-16 gauge for the speakers and 12-14 gauge cable for the subwoofer connection. It is also critical to observe the speaker polarity while wiring the speakers to the amplifier. For this setup, you’ll need to connect the positive terminals of the speaker to the positive amp’s positive terminal-the same case applies to the negative terminals.

On the other hand, if for whatever reason if the factory radio/head unit does not include the preamp outputs, then you’ll need to get the Y-cable adapter to help to divide signals between both amplifiers before you can finally hook up your speakers.

How to install 2 amps in a car diagram

If you don’t have time to go through the above steps, here is a simplified wiring diagram to help you install two amps in a car using one power wire.

How to install 2 amps in a car diagram


One of the reasons why you may opt to go for a second amp is to supplement your main speakers or getting a dedicated amp for the subwoofer. However, while doing so, you want to ensure that your charging system is up to the task to avoid draining the battery. You may also want to consider other factors like the available space in your car trunk and your personal preferences.

The safest and easiest way to hook up two amps to one power source is by using a power distribution block. Besides, using a power block is a great way to ensure your setup is neat while eliminating potential noise issues associated with multiple amp setups.

Avatar for Jamie K. Martin

Jamie K. Martin holds a degree in Audio engineering from Husson University, Bangor. Martin spends most of his time testing and trying the technology he writes about to ensure that he provides first-hand information to our customers from all walks of life.

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