How to Use Factory Amp with Aftermarket Stereo

how to use factory amp with aftermarket stereo

In the world of car audio enthusiasts, upgrading your factory stereo system is a common pursuit. One challenge many face during this process is figuring out how to use a factory amp with an aftermarket stereo. Integrating these two components can be tricky, but with the right information and steps, it’s entirely possible. In this guide, we’ll walk you through the process step by step, ensuring that your car audio upgrade is a seamless success.

Understanding the Basics

Before we dive into the specifics, it’s crucial to understand some fundamental concepts related to car audio systems and factory amplifiers.

1. What is a Factory Amp?

A factory amplifier, also known as a factory amp, is an integral part of your car’s audio system. It’s responsible for amplifying the audio signals and sending them to your speakers. Factory amps are designed to work with the stock head unit, and they often have specific wiring and connectors.

2. The Role of an Aftermarket Stereo

An aftermarket stereo, on the other hand, is a car audio system that you install in place of your factory head unit. These systems offer improved sound quality, advanced features, and often have a different wiring setup than factory head units.

Steps to Use a Factory Amp with an Aftermarket Stereo

Now that we have the basics down, let’s dive into the step-by-step process of integrating your factory amp with an aftermarket stereo.

Research Your Car’s Audio System

The first step is to research your specific car make and model. Different vehicles have varying factory audio systems and factory amp setups. You’ll need to know the wiring configuration, the type of connectors used, and the location of the factory amp. You can often find this information in your car’s manual or through online resources.

Gather the Necessary Tools and Materials

To complete this task, you’ll need a few necessary tools and materials:

Aftermarket stereo unit

Wiring harness adapter compatible with your car

Crimping tool and connectors

Wire stripper

Screwdrivers and panel removal tools

Multimeter (for testing and troubleshooting)

Disconnect the Factory Head Unit

Start by disconnecting the factory head unit from the car’s electrical system. Carefully remove any panels or trim that may be covering it. Use your screwdrivers and panel removal tools as needed. Once you have access to the head unit, disconnect the wiring harness and any other cables.

Connect the Aftermarket Stereo

Now, it’s time to connect your aftermarket stereo. Use the wiring harness adapter compatible with your car to make the connections. Match the wires on the harness with the wires on your aftermarket stereo, following the color-coded or labeled instructions.

Integrate the Factory Amp

To use the factory amp with your new stereo, connect the factory amp’s input wires to the preamp outputs on the back of your aftermarket stereo. These outputs are typically labeled as front, rear, and subwoofer. Make sure to match them correctly to maintain the right channel balance.

Test Your Setup

Before securing everything in place, it’s crucial to test your audio system. Reconnect the car’s battery and power on your new stereo. Play music and check that all speakers are working correctly. Use your multimeter to check the voltage at various points to ensure there are no issues with the wiring.

Secure and Reassemble

Once you’re satisfied with the performance and functionality of your new stereo, secure all the connections, mount the stereo in the dashboard, and reassemble any panels or trim you removed during the process.

Fine-Tune Your Audio

Now that your factory amp and aftermarket stereo are working together, take some time to fine-tune your audio settings. Adjust the balance, fade, equalizer, and other settings to achieve the sound quality you desire.


Upgrading your car stereo system by using a factory amp with an aftermarket stereo is a rewarding project that can significantly enhance your in-car audio experience. By understanding the basics, gathering the right tools and materials, and following the step-by-step process, you can achieve a seamless integration and enjoy the benefits of your upgraded audio system. Remember, if you encounter any difficulties, consult a professional or seek advice from car audio enthusiasts to ensure a successful installation. Happy listening!

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