4 channel amps are a core piece of any car stereo system. These are what you need to connect and power 4 speakers in your car, one for each door. This review looks at the best 4 channel amps on the market. We analyze the features and specifications of each product and put the speakers to the sound test.
Later in the guide, we also share some more information relating to car amplifiers and explain some of the things to think about when choosing one. This will help you to make sure you choose the right one for your car.
Table of Content
- Alpine KTP-445U
- Rolls DA134 4-Channel
- Skar Audio RP-1200.1D
- Rockford Fosgate TM400X4
- Skar Audio RP-75.4ABM
- Alpine S-A32F
- Kenwood 1177524
What Is A 4 Channel Amp?
A 4 channel amp is a device with four channels. It is used in audio applications to amplify the input signals to the desired level. These are typically used in cars and vehicles to power the internal sound system. Although they are also often used in venues for controlling speakers mounted in walls. They provide a central destination to control the volumes and tones for each speaker.
A 4-channel amp is a device that amplifies input signals to the desired level for an audio system. The channels are usually labeled as “front left”, “front right”, “rear left” and “rear right”. This is because when you have a receiver and speakers, the front speakers are on the left side of the room and the rear speakers are on the right side of the room.
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Why Do You Need A 4 Channel Amplifier?
A 4 channel amplifier is a must-have for any car audio enthusiast. The 4 channels provide enough power to drive your speakers and subwoofers, which is necessary for producing high-quality sound.
If you care about the sound quality of your car, then you will care about the quality of your amp. Having a four-channel amp lets you connect up to four sets of speakers, creating a surround rig inside your car.
Four-channel amps don’t come with their own speakers, so you will need to buy them separately. You can connect almost any kind of passive speaker to your amp, provided they have suitable power handling ratings.
The main reason to get a 4 channel amp is to give yourself more control (and volume) over your multi-speaker sound system.
7 Best 4 Channel Amps
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The Alpine KTP-445U is a decent entry-level 4-way amplifier. You can’t expect a huge amount of features or functionality at this price, but it does the job at hand.
This is a Class D amplifier with up to 45 watt RMS power. You can power up to four external speakers with this amplifier provided the power rating is appropriate. This is an effective solution for increasing the volume of your vehicle’s sound system. It won’t make a massive increase in terms of sound quality, as the components in this device are relatively average quality.
This is easy to install and can be wired to the same electrical circuit as the receiver. It uses standard RCA inputs and outputs so you will be able to connect it to most kinds of audio equipment. This makes a noticeable volume upgrade over many stock car amps and is a great way to modify your kit.
- Amp Class – Class D
- RMS Power – 45-watt
- Inputs – Stereo RCA
- Output type – Wired Speaker Terminal
- Controls – Gain
Pros and Cons
- Super easy installation
- Increase volume output of your setup
- Clean, boosted tone
- Limited controls
- Limited features
Simple but effective, this Alpine 4 channel amp is a solid choice for most new audio enthusiasts. This isn’t a top-of-the-range device, but it will be a noticeable upgrade over many standard components. It’s affordable and easy to install, so it’s a great starting point for pimping your ride. Although if you are seeking something with more customization and features, you will need to look elsewhere.
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This Rolls amp is an affordable and effective 4-way distributor. Whilst only offering a minimalist set of features, the Rolls DA134 does a great job at splitting and amplifying audio across 4 channels.
This amp features 4 independent gain controls for each speaker output, meaning you can get a great level of control over the balance of audio in your car. The input connections are easy to get set up, and it connects easily to phones thanks to the 3.5mm aux input.
The main attractions of this amp is its simplicity and reliability. It doesn’t have any extra features like EQ or filtering, but it is a straightforward tool for controlling the audio system of your vehicle.
- Amp Class – Class D
- Inputs – RCA In and Out, 3.5mm aux
- Controls – 4 x independent gain knobs
Pros and Cons
- Can take audio directly from phones, tablets, and laptops
- Independent gain controls to fine-tune the balance
- Easy installation and wiring
- Very affordable
This is a decent little 4 channel mixing amp for use in cars and vans. This would also be suitable for use in venues or similar installations requiring multichannel audio. It is limited in terms of features and tone shaping, but it’s an affordable and reliable solution for those in need of a 4 channel amplifier. If you need 4 separate gain channels on a budget then this is a great choice.
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This Skar Audio series of amplifiers comes in a wide range of classes, wattages, and channel counts. This particular model is a 1200W Class D amp, so it offers a loud tone but requires a fairly large amount of power. You can definitely find the exact specifications you need on this range of amps, so if you like the overall quality then look here.
This range of amps comes with a pretty decent amount of customization, although nothing spectacular. This particular model comes with controls for Gain, a low pass filter, and a bass EQ crossover. You can get fairly good control over the low end of your sound system, although there isn’t much for the mids and highs.
The inputs of this amp are fairly limited too, with only a single pair of stereo RCA connectors. Although this is enough for most situations and will be fine if you pair it up with another receiver to handle switching between input sources like CD, Radio, Phone, etc.
The overall sound quality of this amp is decent, and it has a clean tone with little interference. You can find amps of all strengths and sizes in this range, so if this particular model is too loud or quiet, check some of the other models.
- Amp Class – Class D MOSFET
- Peak Power – 1600 watt
- Inputs – Stereo RCA
- Controls – Gain, LPF, Sub crossover, Bass EQ
- Frequency range – 20Hz – 250Hz
Pros and Cons
- External Remote bass control knob
- Excellent heat stability
- Overload protection circuit
- Ideal for using subwoofers.
- Not a true 4 channel
There is something for everyone in this amp series. You can find any type of specifications you need. For example, you can find a couple of 5 channel models on the lineup, which have the capacity to power four speakers and an additional subwoofer.
Overall, these amps are well made and have no noticeable issues. They aren’t packed full of features but offer a little more than the most basic models.
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The Rockford Fosgate is a high-end four-channel amplifier. This is not a basic model, nor is it cheap, making it a serious investment for car audio enthusiasts. With a huge amount of powering and features, this amp blows many out of the water and is probably one of the strongest contenders on this list.
This amp features two independent channels of equalization, with separate circuits for the back and front speaker outputs. This lets you fine-tune the sound difference between the back and front of the car. This is useful if you want to give the passengers a modified sound.
This model is also exceptionally durable and strong. It features a water and dust-proof chassis that can withstand a large amount of use and abuse. It comes with a whole range of useful functions and offers a lot more than your standard affordable amps.
This thing is pretty expensive, but it’s definitely worth the money if you want something next level. It offers the famous build and sound quality that Rockford is known for, and it will handle years of full-scale use.
- Amp Class – AD Class
- Peak Power – 400-watt
- Inputs – Molex Style connectors
- Controls – EQ boost/cut, frequency, input level, filtering
Pros and Cons
- Super high-end sound quality
- Top-level build
- Powerful features
- Easy connection
- Overkill for basic setups
If you have the money, this is probably the best amp on this list. It has the most extensive features yet, the best powering, and superior sound quality to many other amps. These are much better investments than cheaper units and will yield better results for much longer.
This amp has a really impressive sound and gives the user a decent amount of control over the tone. I really can’t recommend this enough! My only issue is the price which puts it out of reach for many people. This almost costs as much as a cheap car!
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The RP75 is another high-quality A/B class amplifier from industry express Skar Audio.
This amp provides a split 4-way input, so you can pipe four independent channels to and from this amp. This enables you to create a setup with more depth than stereo and works in a surround format. This is a lot of fun to play with and gives the music you listen to a whole new dimension.
Another main selling point of this amp is the independent channel controls. Each pair of channels has an independent set of controls. This allows you to shape the sound of the speakers differently between the front and back of your car.
The controls include a separate control, an HPF with cutting from 20Hz to 5kHz, and an LPF from 50Hz to 500Hz. Each channel also has separate switches for crossover frequencies and bass EQ boosts. This lets you change the balance of bass and highs between the front and back of your car.
This amp is available in a range of wattage ratings, from 500 to 1500. So you should be able to find a range that works with your speakers.
These amps can crank pretty loud, so if you’re looking to get a bit of extra volume in your rig then this is a good place to start. The sound isn’t overwhelmingly high quality, although it’s definitely good enough for most situations, and won’t disappoint.
- Amp Class – A/B Class
- RMS – 500-watt
- Inputs – 2 pairs of stereo RCA
- Controls – 2 x Gain, 2 x HPF, 2 x LPF, Crossover, Bass EQ
- Extra Features – Overload protection, remote control input
Pros and Cons
- Fully waterproof enclosure
- Super low signal to noise ratio
- 2 Separate input channels with independent controls
- No Remote control
If you need an amp that has four channels, and allows for a bit of customization between them, this unit from Skar Audio is a great place to start. It has a lot more flexibility than many amps on this list and sounds great too. The main attractions of this amp are the simple setup, and how much you can tweak it. There aren’t many advanced features, but what it has it does well.
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This is another amp from Alpine and offers a lot more features and functionality than the Alpine amp from earlier in this list.
This amp offers up to four input and output channels and provides up to 160W RMS across four speakers. The inputs are all stereo RCA connections, so they can be easily connected to most sources.
The amp also includes a few controls, separated for each channel. These controls include a gain knob, a switchable HP/LP filter, and a variable cutoff control. It also includes a remote control input which can be used to change the level of the channel 3/4 gain.
This unit has a relatively decent sound, although it is lacking in some areas. It competes pretty well with most amps, although is beaten by more expensive units like the Rockford.
The housing and enclosure of this device are pretty solid and don’t take up too much room. We generally liked this amp, although it would be good to see a little more depth in the provided controls, and perhaps some more independent channel gains.
- Amp Class – D Class Digital
- RMS -160W x 2
- Inputs – 2 x Stereo RCA
- Outputs – 4 separate speaker terminals
- Controls – 2 x Gain, 2 x Variable Filters, HPF, LPF
Pros and Cons
- Surround style multi-channel inputs
- Independent controls for each channel
- Remote level control
- Low Impedance
If you’re looking for a small and sophisticated four-channel amp, this Alpine model could serve you well. These are a step above the most affordable models, and whilst the price is a bit higher, the improvement in quality and control is noticeable. This particular model offers some great bass-boosting functionality and can handle four speakers with ease.
This is highly recommended for people seeking an improved, but still affordable amplifier, with a few extra features and quality components. If you have a spare budget, I would recommend looking for something with a little more diversity and functionality, but this will still suit most people.
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This Kenwood amplifier is an ideal design for motorcycles and all-terrain vehicles. It’s highly dust and water-resistive, so you can rest assured that this can handle the threats of the outdoors.
Whilst small in size, this is still a pretty powerful amp, with a peak rating of 400 watts and an RMS of 180W. This can power up to four speakers and has a good level of control and tuning.
It offers four inputs and outputs. Each input has its own gain knob so you can get a great balance across all speakers. It also has a switchable bridging mode, so you can run it as a 2 output amp rather than 4. This bridging mode would give the speakers some extra oomph and substantially increase their volume.
The way this unit is designed is geared more toward four-speaker setups and has a fader control for setting the balance between the front and rear pairs.
The main selling point for this amp would definitely be the Bluetooth input. You can wirelessly connect any Bluetooth device to this amp and stream audio through it. This is a gamechanger and can help to streamline any setup by removing wires. It also comes with a remote control that syncs and controls your Bluetooth devices. This control has buttons for volume up/down, song skipping, and play/pause.
The remote control feature is a huge bonus and enables this amp to integrate seamlessly into any vehicle.
- Amp Class – Class D
- Peak Power – 400 watts
- RMS – 180W
- Inputs – Built-in Bluetooth
- Controls – 4 Channel, or 2 Bridged Channel Switch, Line In and Out Gain
Pros and Cons
- Fully Waterproof – Ideal for motorcycles or ATVs/
- Includes remote control
- Bluetooth input
- Limited power
This is really a fantastic amp, with an excellent set of features. This uses a lot of modern design techniques to make it more effective, useful, and intuitive. No longer do you have to awkwardly reach around to find a volume knob. You can have it wherever you want with the remote control.
It lets you get a great balance across channels and even lets you control your phone or Bluetooth player. The powering is pretty decent too, and this can feed relatively beefy speakers. The sound quality is more than acceptable. The only real criticism is the lack of any kind of EQ, and also the lack of a wired audio input. This thing only receives audio from Bluetooth devices, so it won’t be suitable for everyone.
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A Pocket Guide to Buying a 4 Channel AMP
When choosing a 4 channel amp, there are several factors you should consider. The following sections provide you with some extra information to help you make your decision. These factors can have a large impact on the style of amp you should choose, so make sure you take the time to properly assess the situation and your desires for a particular type of Soundsystem.
One of the most important things to get right is the power requirements and supply of the amp. If you are powering it directly from the car battery then make sure it matches the power rating. At the same time, you need to match the power rating between the speakers and the amplifier. Otherwise, you risk blowing or underpowering the speakers.
You want to make sure that the amp you choose has the right connections for your speakers. It also needs to have the right input connections to connect it to your source device. Most car audio gear uses RCA connectors, or similar. If you are considering getting more connections like Bluetooth or aux input, then factor this into your decision.
You should choose an amp that has the right controls for your preferences. You may only need something with basic volume control, or you may want something more sophisticated with equalizers, panning, and presets. The choice is yours.
The class of the amp is a categorization based on the efficiency of its power usage. The two most common types are A/B and D. A/B Amps use much more power but have a much higher level of audio quality. Class D amps are more power-efficient but have a weaker sound.
How To Choose The Best 4-Channel Amp?
There are a few steps you can take when choosing a new amp to make sure you get the best one for your needs.
First, you need to think about the kind of setup you are trying to make. Do you want an amp that has a lot of controls and functionality, or are you just in need of something that provides a simple but effective solution for powering multiple speakers?
Once you’ve figured out what your main use case will be, it will help you to search for the right properties.
The main things to think about are hope accessible you need the amps controls to be. This will determine if you need to go for something that has a remote control, or if it has another easy way to change the settings.
The other thing to consider is the balance between volume and power. More volume requires more power and more power handling in your speakers. This generally costs more, but if the volume is what you want, it’s a necessary purchase.
How To Bridge A 4 Channel Amp
Bridging your amp is a smart way to maximize the volume output.
Many car amplifiers have a bridging mode, which involves combining two channels into one to boost the maximum output. This is useful for squeezing every last drop of volume out of your setup.
If you have a 4 channel amp, and only plan on using one pair of speakers, you can nearly double the power of each one by combining the inputs.
Here are the steps to follow to bridge a 4 channel amp.
- Find the terminals on your amp, there will be outputs for both negative and positive terminals for each channel.
- Use a Speaker wire to connect the positive terminal of the first channel to the positive terminal of the first speaker. Use the clamps and a screwdriver to lock the wire to the terminal.
- Use a speaker wire to connect the negative terminal of the second channel to the negative terminal of the first speaker. Again, clamp the wire to the terminal as required
- Repeat the above steps for the 3rd and 4th channel of your amp with the second speaker of your setup. The last step is to connect Channel 4’s negative terminal to the second speaker.
- Your amp is now connected in bridge mode! Enjoy your new boosted volume.
Can You Connect 4 Speakers And A Sub To A 4 Channel Amp?
Generally not, unless it has an extra sub output. Amplifiers with 4 channels are usually limited with 4 outputs. This means you can only attach up to 4 speakers at a time. If you want to use 4 speakers and a sub then you will need a 5 channel amp. You could even go for something with more channels and use multiple additional subwoofer speakers for max bass.
If you split the output of your original source, you could split it between a 4 channel amp and a sub amp, this would let you use 4 speakers and a sub, although you are using two amps instead of one. It would be a lot more efficient just to use a 5 channel amp if you want to include a sub in your setup.
How Many Speakers Can a 4 Channel Amp Power?
Typically a 4 channel amp can power up to four speakers, although it depends on the power strength of the amp in relation to the speakers. You can use a 4 channel amp with 2 speakers in bridging mode, to get more aggressive levels of volume. Some amps even come with quick switches for changing between these modes.
If your amp is underpowered for the speakers, it may struggle to play four speakers at full volume. Because of the diminished distribution of energy, the speakers may not receive the level of power they need to function properly.
Will a 4 Channel Amp Make a Difference?
Depending on what your previous setup involved, a 4 channel amp could be a big upgrade. This will definitely have more power than a lot of stock setups.
Depending on how much you spend, it could be a very noticeable upgrade over previous amps. You can find amplifiers that add as much power as you can imagine. So you will definitely be able to find an amp that makes an improvement over your current setup.
The most noticeable difference would be in sound quality, volume, and power usage. These factors are also interlinked.
Thanks for reading this guide on the best 4 channel amps. You should now have an excellent understanding of the best models available on the market. This should help you to choose a fantastic amp for your car.
If you are interested in upgrading the bass response of your car’s sound system, check out this guide on the best under-seat subwoofers, for maximum subs!
Noah is an accomplished audio engineer with several years of experience producing music for major companies and independent artists. He enjoys sharing his vast knowledge of audio engineering topics to help musicians and music producers create great music.