You’ve decided to add an aftermarket subwoofer and amplifier but, you want to keep your stock head unit. Your stock head unit will more than likely not have the RCA preamp outputs to connect an amplifier to. So, how do you install an amplifier in your vehicle? Some amplifiers will have what are called high-level inputs. This allows you to tap into your vehicle’s stock speaker wiring to send a signal to the amplifier. But, what do you do if your amplifier doesn’t have the speaker or high-level inputs? Enter the line output converter or LOC. In this post, we will discuss what a line output converter is and how to go about installing one into your vehicle to properly install your aftermarket amplifier.

What is a Line Output Converter?






A line output converter is a device that allows you to convert a speaker, or high-level, output into the traditional RCA type preamp-level output connections that are typically found on all aftermarket amplifiers. This will enable you to connect your stock head unit to an aftermarket amplifier.

Installing a Line Output Converter

Installing a LOC is fairly straightforward. You are basically going to tap into your stock speaker wiring and connect these speaker connections to the line output converter. You are probably asking, “Where do I tap into the speaker wires?” Good question. It will all depend on the vehicle. Most sedans will have speakers located within the deck behind the back seat. This is the perfect place to tap the speaker wires and grab the signal for your line output converter. The wires are easily accessible from the trunk. In other vehicles, you may have to tap into the speaker wiring from behind the head unit, or from the speakers inside the door. Both of these can be more involved, but by doing some research on your vehicle’s wiring and how to disassemble the trim panels, you should be able to do this without too many issues. 

NOTE: Keep in mind that, in addition to the speaker-level wiring, you will also have to run power, ground, and remote turn-on wire for most LOCs.

Basic LOC Setup Example           

       basic LOC setup


Speaker Connections

If you are installing a single amplifier, such as a monoblock for a subwoofer, you will want to only tap into the stock speaker wiring and run the necessary wiring to the LOC without completely disconnecting the speaker. This will allow you to connect the LOC and provide the needed signal for it to function and will also keep the speaker functional within your stereo system. 

On the other hand, if you will also run an amplifier for the speakers within the doors, dash, or rear deck, then you will want to disconnect these speakers because you will need to run new speaker wiring from your amplifier into the doors, or other locations, to the speakers. In this case, it is ok to cut the speaker wiring instead of just using the tap method.

Line Output Converter Differences

In order to determine which LOC will work for you, you should be aware of a few things. There are ample choices when it comes to choosing a line output converter. Some LOCs will include different features, such as gain adjustments, and will have varying RMS power handling capabilities. You will have you make sure your stock head unit’s RMS power rating falls within the recommended power handling of the line output converter.

Some other features to consider when choosing which line output converter to choose are BASS restoration, EQ adjustments, and high-voltage preamp outputs. The higher the output voltage will ensure that the audio signal from your LOC to your amplifier will remain clean. Some of the lesser expensive LOCs will add distortion to your amplifier’s audio signal.

All of these features are great to have if you want more control over tweaking your system, but they will also come at a cost. My recommendation is to find a line output converter that meets the needs of your system and that is most important to you so that you can stay within your specific budget.

Other Uses For a Line Output Converter

In certain installation cases, a line output converter can be used to install an aftermarket head unit into a vehicle with a factory-equipped amplifier. The line output converter is used in addition to vehicle-specific integration wiring harnesses to allow the higher RMS-rated head unit to connect to the factory amplifier without issues. This is also where the more feature-rich LOCs will come in handy. Things such as gain adjustments and EQs can be used to balance the audio signal in order to provide the best possible sound quality from the factory amplifier and speakers.


If you have decided to keep your factory head unit, but want to install that killer amp and subwoofer, I hope this post has provided you with some basic information in regard to line output converters.

Line Output Converters - What Are They - How Do You Install One?

About The Author Brandon L

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