How to Wire The High Level Input on An Amp

Norvan Martin
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When wiring the high-level input on an amp, there are a few things you need to keep in mind. The first is that the high-level input should be wired directly to the amplifier’s speaker outputs. This will ensure that the best possible sound quality is achieved.

Additionally, you’ll need to make sure that the RCA cables are properly terminated. If they’re not, you may experience sound degradation.

Next, you’ll need to make sure that the amplifier is turned off before making any connections. This will help prevent damage to the amplifier and the RCA cables.

What Is High-Level Input On an Amp?

In audio terminology, high-level input is a signal that has been amplified before being input into the device. This is in contrast to low-level input, which is a signal that has not been amplified.

High-level input can be helpful when you want to boost the volume of a weak signal. It can also provide a cleaner sound quality than low-level input since there is less noise and distortion introduced by the amplification process.

However, high-level input can also be more susceptible to interference from outside sources, so it’s important to take steps to minimize these distractions.

Methods for Wiring High-Level Input On An Amp 

When installing an amplifier with high-level inputs three main methods can be used: speaker wire, RCA cables, and remote turn-on wire.

Each of these methods has its advantages and disadvantages. We will detail each method so you can determine which is best for your installation.

Method 1: Speaker Wire Method

The first method uses a speaker wire to connect the amplifier directly to the factory stereo. The speakers are typically left intact with this type of installation, although cutting them out may make it easier to run the wires between the amp and the factory stereo (if you decide not to use them).


If this method is used, be sure that there is enough clearance between the amplifier and the driver’s side firewall (or wherever you decide to mount your amp).

Method 2: LOC (Line Level Converter) RCA Cable Method

For this method, a line output converter (L.O.C.) converts high-level signals into low-level ones.

Step 1: Get to know the Line Output Converter (LOC). It usually comes with seven different colored wires. On its input side, you have yellow for the power input; solid white for the left channel positive; white with a stripe for the left channel negative; solid grey for the right channel positive; grey with a stripe for the right channel negative; and Black for grounding. On the output side, there’s a Blue wire for sending signals to your amp or connecting to a remote.

Step 2: Take a look at your vehicle’s wire diagram or connector guide to figure out which LOC wire matches up with your car’s wires. Every car has its own setup for wires. After you find the matching wires in your car, you’re ready to connect them.

Step 3: For instance, let’s join the left channel positive wire. Chop the corresponding wire from your car’s set in half, so you’ve got two ends, and then take one end from the LOC. Strip a bit of the covering of each of these three ends with a wire stripping tool.

Step 4: Hold up one end of your car’s left channel positive wire next to the LOC’s left channel positive wire. Twist them together carefully to join them.

Step 5: For a firm hold on this connection, put the twisted ends into one side of an electrical connector and clamp it tight with a crimping tool.

Step 6: Now with the remaining wire end — that is, the other half of your car’s left channel positive wire — pop it into the available side of the connector and give it another crimp. This means all three left channel positive wires are now joined neatly.

Step 7: Do the same process for all the matching wires. After you’re done, wrap them up nicely and snug in some electrical tape to keep everything tightly together.

Step 8: Last of all, connect RCA plugs to the LOC outputs. This will make it easy to hook up a high-level signal input on an amplifier, which is great not just for normal radios but also subwoofers with high-level inputs, just like the video tutorial shows.


The converter’s RCA output wires are then connected to the amplifier, and a power wire from the car battery is connected to the L.O.C.’s power supply (usually an accessory fuse).

By converting speaker signals into pre-amp signals, this method allows for amps with high-level inputs to be installed in locations far from the factory radio without having to rewire speakers or run new speaker wires.

Method 3: Remote Turn-On Cable

This cable has a small box that sends a 12-volt signal when you turn on your car. It can be plugged into a cigarette lighter or accessory port under your car stereo (if available).

The amp will only turn on when it senses this voltage which means that there won’t be any power drawn from the car battery when the stereo is off. This is a great option if your amp doesn’t have a remote turn-on wire.

No matter which method you choose, be sure to follow the wiring instructions that come with your products.

How to Wire The High Level Input on An Amp Diagram

Amplifier High-Level Input Vs Low-Level Input

There are two ways to input audio into an amplifier: high-level and low-level. Each method has its advantages and disadvantages, which can be summed up as follows:

High-Level Input:


1. Easy to set up – all you need is a standard RCA cable.
2. No power required – the amplifier gets its power from the head unit.
3. Works with any head unit – no special equipment or settings needed.
4. Can be used with aftermarket or factory head units.
5. Less likely to cause interference than low-level input.
6. More reliable signal transmission than low-level input.
7. Cheaper than low-level input.


1. Can only be used with head units that have preamp outputs or line outs 
2. Signal loss at high volumes is more likely than with low-level input.
3. Uses up one of your head unit’s RCA preamp cables.
4. May require an inline resistor to prevent overloading the amplifier’s inputs
5. Potential ground loop problems if you run both high- and low-level inputs into the same system simultaneously.

Low-Level Input:


1. More versatile than high-level input
2. Less susceptible to interference from nearby components
3. No power required – the amplifier gets its power from the head unit.
4. More reliable signal transmission than high-level input.
5. Cheaper than high-level input.


1. Signal loss at high volumes is more likely than with high-level input.
2. Uses up one of your head unit’s RCA preamp cables
3. Potential ground loop problems if you run both high- and low-level inputs into the same system simultaneously.

Which input method you should use ultimately comes down to personal preference and the features of your head unit. If you have a head unit with preamp outputs or line-outs, then high-level input is the way to go. This is because it’s easy to set up, less likely to cause interference, and more reliable than low-level input.

If your head unit doesn’t have preamp outputs or line outs, then you can still use an amplifier with low-level input by using an auxiliary input adapter. However, if you don’t mind spending a little extra for convenience and simplicity or already have an amp with a low-level input, then high-level input may not be right for you. The choice is up to you.

Amp High-Level Input Connector

An amp with a high-level input connector can be easily connected to an OEM radio without any modification.

This is ideal for those who want to add an amplifier to their vehicle but do not want to have to cut into the factory wiring.

Simply connect the power and ground cables from the amp to the corresponding connectors on the back of the radio, then run the signal cable from the amp’s output connector to the high-level input on the amp.

When installing an amplifier with a high-level input connector, you must use a quality RCA cable. A cheap RCA cable may not be able to handle the increased current flow and could potentially damage your amplifier. Always use an RCA cable that is specifically designed for amplifiers.

What Is High-Level Input On Subwoofer

Good high-level input for your subwoofer will ensure that you’re getting the most out of your speaker and your overall sound system.

When shopping for a new subwoofer, be sure to pay attention to the specs and make sure that it has an adequate high-level input.

Most subs have this type of input these days, but there are still some older models out there that only have speaker wire terminals.

How to Connect High-Level Input Subwoofer?

Step 1: Identify the input of the subwoofer: This can be done by checking the owner’s manual or contacting the manufacturer.
Step 2: Identify the output terminals on the amplifier: There will usually be two, one for left and one for right channels.
Step 3: Identify which terminal is positive and which one is negative: This is by looking at the diagram on the amplifier.
Step 4: Connect the speaker wires: Connect each speaker wire from the input subwoofer to its corresponding output terminal on the amplifier using a crimping tool or pliers. Make sure that there are no loose wires before moving on to the next step.
Step 5: Secure all connections with electrical tape.
Finally, test out your new set-up by playing some music.

4 Channel Amp High-Level Input

The high-level input on a four-channel amp is designed to accept the output of a head unit or other audio source.

The signal from the head unit is sent through the RCA cables and into the amplifier. This type of input is ideal for systems where there is not enough space to install an amplifier with dedicated inputs for each speaker.

The high-level input on a four-channel amp should only be used as a temporary solution. The signal from the head unit is amplified and sent to all of the speakers in the system. This can cause distortion and damage to the speakers if it is used for an extended period.

It is recommended that you use an amplifier with dedicated inputs for each speaker whenever possible.

How to Wire Up A High-Input Amp

There are a few different ways to wire up an amplifier, but we’re going to focus on the high-input amp wiring diagram.

This type of wiring is popular in cars and trucks because it allows you to use the factory stereo’s signal to power your new amp.

Step 1: Find out Which Wires are for Audio signals

To start, you’ll need to find out which wires in your car’s stereo harness are for audio signals.

Usually, these will be red and white, but they can vary depending on the make and model of your vehicle. Once you’ve identified the audio signals, connect them to the corresponding inputs on your amplifier.

Step 2: Connect The Ground Wire

Next, take the ground wire from your amp and connect it to a good ground point in your car. The best place to do this is usually your car’s battery.

Step 3: Connect The Power Wire

Connect the power wire from your amp to a fused ignition-switched power source in your vehicle. If you’re not sure where it is located in your car, refer to your owner’s manual.

Then run another ground wire from this same point and attach both ground wires to the body of the vehicle with self-tapping screws. This will help keep electrical noise away from all of your audio equipment for cleaner sound quality.

5 Pin High-Level Input Connector Diagram

The diagram below shows the typical connector pinout for a high-level (five-wire) input.

The five pins are:

  • Power
  • Ground signal input
  • Enable input
  • Feedback output

The power and ground pins should be connected to your vehicle’s battery and ground, respectively. The signal input is the wire that will receive the signals from your sensors. The enable input is used to control whether or not the sensor signals are being read by the ECU.

The feedback output is used to send back information to the ECU about how much voltage was applied to the signal input. This can be used to determine things like the pedal position or throttle position.


Now that you know how to wire the high-level input on your amp, it’s time to start enjoying your music. Just be sure to stay safe while you’re wiring, and always consult a professional if you’re unsure about anything. With a little bit of practice, you’ll be able to wire your amp like a pro in no time.

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Norvan Martin is the founder of He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin