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Published Jan. 14, 2020

When you buy a vehicle it typically comes with a basic audio system. If you really love music and prefer to hear hard-hitting bass and crisp, clean highs and mids, then you may want to invest in some aftermarket audio equipment, such as a 4-channel amplifier.

Our buying guide below features some of the best 4-channel amplifiers on the market. Whether you’re looking to buy the best 4-channel amp for the money or you’re an audiophile who doesn’t mind spending a little more money for a premium model, we’ve got you covered.

The Best 4-Channel Amplifiers

This high-quality amplifier is very versatile. It delivers 50 watts RMS to the front and rear speakers in the four-channel mode. You can also power two speakers and a subwoofer in three-channel mode or use it in two-channel mode to power two subwoofers. 

The amp adds clean and precise power to your system at an affordable price. It’s compact, and it’s fairly easy to install. While the Alpine is a quality, powerful amp, the terminals could be more secure. Also, it can get very hot, and one of the channels may stop working after less than one year of use.

Key Features
  • 50 watts RMS x 4 at 4 ohms 
  • 150 watts RMS x 2 bridged output at 4 ohms
  • Class D
  • MOSFET power supply
Specification
  • Brand Alpine
  • Model MRV-F300
  • Weight 4.6 pounds
PROS

Versatile

Clean, precise power

Compact and easy to install

CONS

Terminals are not very secure

Heats up easily

Channels may stop working  after a short period of use

The class AB amp has 3,200 watts peak output and a fully adjustable 12 dB/octave crossover. It also includes a subsonic filter, a fully adjustable bass equalizer, and mute and delay soft start technology. It’s a great amp for mids and highs. It delivers a clean, loud, and powerful sound.

While the amp is easy to install and it has lots of configurations so you can get what you need for your speaker system, it can get very hot, causing it to go into protection mode quite easily. However, that may be due to improperly set gains. Still, you need to be careful where you put it because of the heat it generates.

Key Features
  • 2 Ohm: 400 Watts x 4 Channel
  • 4 Ohm: 270 Watts x 4 Channel
  • MOSFET power supply
  • Class AB
Specification
  • Brand Rockville
  • Model dB45
  • Weight 13.55 pounds
PROS

Great mids and highs

Clean, powerful sound

Easy to install

CONS

Gets very hot

Goes into protection mode easily if not properly set up

You must be mindful of its position in the vehicle

This Alpine amp works great in both four-channel and two-channel mode, the latter of which can operate two subwoofers at 350 watts RMS each. It’s compatible with almost any audio system and delivers a wide frequency response. The thermal flow chassis prevents the unit from overly heating or stressing the electrical system. It produces crystal clear mids and highs at any volume level.

It delivers a wide frequency response, it’s easy to install, and it features gold-plated RCA inputs, outputs, and power connections to prevent corrosion and signal deterioration. You can access the tuning controls through a removable top panel and paint the trim of the device to match your vehicle’s interior. The major drawback is this amp is a little pricey compared to some of its competitors. Also, like all amps, it can get a little hot during operation.

Key Features
  • 350 watts RMS x 2 at 4 ohms bridged 
  • Class D
  • Gold-plated RCA inputs
  • Thermal flow chassis
Specification
  • Brand Alpine
  • Model X-A70F
  • Weight 8 pounds
PROS

Versatile and compatible with most systems

Wide frequency response

Crystal clean mids and highs

CONS

Expensive

Gets a little hot

This compact “power pack” amplifier from Alpine provides a lot of punch for its diminutive size. It’s extremely compact size means it can be tucked away in the dashboard. The amp can boost your receiver’s output by 45 watts RMS by four channels or it can be bridged for 2 x 90 watts. Overall, the amp sounds great, and there is a noticeable increase in volume to your system.

The unit is very easy to install and efficiently uses the factory wiring, and there is no need for a separate power source other than the factory harness that is powering the head unit. However, there may be some white noise after installation, and there may be a hissing sound at low volume unless the gain is reduced to near zero. There may also be some background distortion noises.

Key Features
  • 45 watts RMS x 4 at 4 or 2 ohms
  • 90 watts RMS x 2 bridged at 4 ohms
  • Class D
  • Selectable high-pass filters
Specification
  • Brand Alpine
  • Model KTP-445
  • Weight 2.4 pounds
PROS

Small enough to fit in the dashboard

Noticeably increases volume

No need for a separate power source

CONS

Possible white noise after installation

May hiss at low volume

Background distortion

This amp drives 50 watts RMS to each speaker in four-channel mode, or you can run two subs at 150 watts RMS each. Its high- and low-pass filters boost performance, and it has over-current and short-circuits protection. The amp has plenty of power and perfectly pushes component speakers. It sounds very clean and distortion-free right up to maximum volume.

While some users have claimed it delivers better RMS wattage than advertised, there have also been some complaints about its performance. It has a tendency to warm up and can go into protection mode fairly easily. It may also get stuck in protection mode and will not reset. It may also stop working after a few months of use.

Key Features
  • 45 watts RMS x 4 at 4 or 2 ohms
  • 90 watts RMS x 2 bridged at 4 ohms
  • Class D
  • Selectable high-pass filters
Specification
  • Brand Rockford Fosgate
  • Model R300X4
  • Weight 7.5 pounds
PROS

Small enough to fit in the dashboard

Noticeably increases volume

No need for a separate power source

CONS

Possible white noise after installation

May hiss at low volume

Background distortion

This class D amplifier sends 100 watts RMS to each speaker, or you can bridge the channels to power a sub with up to 300 watts RMS. It features high- and low-pass filters, so you can adjust the sound depending on whether you’re driving speakers or subs. The amp is compact, efficient, and produces great highs and mids. Overall, it delivers a clean, crisp sound with plenty of power.

The amp is two-, three-, and four-channel operational and is stable at 1, 2, 4 and 8 ohms. One of the downsides is one or two of the channels may stop working after a short period of use. It may also cut out intermittently or at higher volumes and go into protection mode too easily. Also, you may not like the bright blue light on its display.

Key Features
  • 100 watts RMS x 4 at 4 ohms
  • 300 watts RMS x 2 bridged at 4 ohms
  • Class D
  • Variable high- and low-pass filters
Specification
  • Brand Pioneer
  • Model GMD8604
  • Weight 6.3 pounds
PROS

Compact and efficient

Great highs and mids

Clean, crisp sound

CONS

Channels may stop working prematurely

May cut in and out

Can enter protection mode too easily

Best 4 Channel Amplifier Buying Guide & FAQ

A four-channel amp outputs power through four separate channels. At a minimum, it powers two sets of full-range speakers, but it can also power two subwoofers or a single dual-voice-coil subwoofer. When you upgrade your OEM speakers and add an external amplifier to your audio system, it makes a significant difference in sound quality. You have more control over your speakers’ balance and fade, for example.

If you want to drown out road noise, an amplifier’s clarity can do so with little to no distortion. In a nutshell, the top 4-channel car amplifiers deliver more power to your front and rear speakers.

Do You Need a 4-Channel Amplifier?

It doesn’t matter if you prefer heavy metal, pop, or classical music—if you enjoy turning up the volume while you’re on a road trip or simply driving to work, you want the cleanest and clearest sound possible coming out your car speakers. That’s why you need the best 4-channel amp for sound quality.

A 4-channel car amplifier enables you to upgrade your car stereo for the best highs, mids, and lows. Your vehicle’s factory system cannot provide the bass-thumping lows or crisp notes an amplifier can provide. If you want more power in your audio system, you need to invest in the best 4-channel amp.

Benefits

  • An amplifier delivers a cleaner signal to your speakers compared to your vehicle’s factory head unit.
  • When you upgrade your speakers, an external amplifier provides the optimal amount of power in order to produce the best sound possible.
  • If you want to add a subwoofer to your audio system, you need an amplifier because a sub requires more power than the speakers do.

Installation of electrical cables in car audio system

The Most Common Types of 4-Channel Amplifiers

While most amplifiers can be classified into class A, B, AB, or D, we will focus solely on AB and D, since most car amplifiers fit into these two categories. There are also other variations, such as BD. Typically, other amplifier classes include characteristics from the main types of amps to boost performance.

  • Class AB

Class AB amplifiers are a combination of class A and class B. They are much more efficient than class A amps but don’t have as much distortion as class B amps. As a result, many car audio systems use these types of full-range amps. Essentially, the transistors have a constant current flowing through them, but when no signal is present, they reduce the amount of the current in the circuitry. Class AB amplifiers are analog.

  • Class D

Class D amps rapidly switch the current on and off to the transistors. This results in a switched or pulsed output signal. These types of amps are very efficient; however, the switching can cause distortion in higher frequencies. To combat this issue, amps will include a low-pass filter because lower frequencies don’t experience the same problem. The power of class D amps makes them very popular in-car audio systems.

Features to Look for in a 4-Channel Amplifier

Once you’ve decided to invest in the best 4-channel car audio amplifier, there are several things you need to take into account before making a purchase. While many of them feature similar tuning settings such as level or gain, crossover, frequency adjustments, variable bass boost, and subsonic filters, there are other things you need to take into consideration. They differ in the amount of power they produce and in their size, for example.

  • Power

Watts per channel and impedance refer to the amount of power your amplifier can push to the speakers. Peak power or wattage refers to how much power is pushed out in a single burst, while RMS (Root Mean Square) wattage is the constant rate of power that’s pushed through each channel. The power of the amp should be more powerful than your speakers and subwoofer. As for impedance, the higher it is, the lower the RMS wattage per channel. The impedance is rated in ohms.

Speakers with a top RMS rating of at least 50 watts are fine for smaller vehicles, such as sports cars and hatchbacks. If you have a bigger vehicle or want more volume, look for an amp with at least 75 watts RMS per channel. Amps with 100 watts RMS or more per channel will produce even greater volume.

  • Size

Some vehicles have more space for audio equipment than others. If you have a hatchback, for example, space is at a premium, and you may need the best compact 4-channel amplifier. Determine where you’re going to put the amp, and look at the dimensions before making a purchase. You may put it under one of the seats, in the trunk, or next to the passenger-side firewall.

Fortunately, technology has advanced to the point where you can find several small amps that have the ability to produce clean audio. They may be tiny, but if they’re high-quality and made by a well-known brand, they can produce a mighty punch.

  • Compatibility

If you’re using the factory head unit on your vehicle, it probably won’t have preamp outputs because they typically aren’t manufactured with them. As a result, you need to use an amp that has speaker-level inputs. This will produce a better sound than the system provides without an amp, and you won’t need to use additional adapters or wires.

If you’re designing a completely new audio system in your car, you will require a head unit that has preamp outputs and an amplifier with line-level inputs. To get the clearest sound, you should provide an unamplified signal to the amp.

  • Other

When you’re buying a new amplifier, stick to brand names such as Kenwood, Pioneer, Alpine, and JL Audio. They have forged a reputation in the industry and are well known for the quality products they produce. If you buy an off-brand, it may not be as reputable, and the product may be inferior. This can be particularly problematic with electronics because it can be dangerous.

Also, think about how much you have to budget for the amp. They vary widely in price, depending on who makes them and the quality of audio they deliver. You can spend hundreds to thousands of dollars for the best high-end 4-channel car amplifier.

Tips for Buying and Using a 4-Channel Amplifier

Once you’ve decided to upgrade your stereo system with an amplifier (and possibly a subwoofer), then you’ve already committed to enhancing the listening experience in your car. Even if you already have an amp and sub installed in your vehicle, they may not be providing the pop that you want from your music, particularly if they don’t have the wattage you desire.

If you’re creating a custom sound system, there are some things you need to remember in order to set everything up properly. It’s easy to make mistakes if you don’t pay attention to the specs of the various components in the audio system.

  • When selecting an amp, buy one that is more powerful than you need. Look at the RMS of the speakers and sub. Additional power will boost the depth of the music.
  • Be careful not to overload your amp. Make sure it is compatible with the number of ohms that you will be wiring it up to.
  • Pair the amp with aftermarket speakers because your factory speakers may not be compatible.
  • Many people will be satisfied with an amplifier that provides just 50 watts per channel because it will deliver enough volume in most types of vehicles.

Car sound receiver

Best 4-Channel Amplifier FAQ:

A four-channel amplifier is the most common type of amp on the market. Still, you may have some questions about its functionality and how it compares to other types of amps.  If you’re still not sure of the purpose of a 4-channel amp or have other basic questions about its operation, we’ve included some common questions and answers below.

Q: What is a 4-channel amplifier?

A 4-channel car amplifier amplifies an electrical signal and sends it through each one of its channels to the speakers. Four-channel amps generate equal power through each channel.

Q: What’s the difference between a 4-channel amp and a 2-channel amp?

A 4-channel amp powers either four speakers or two front speakers and a sub with two channels bridged. The main purpose of a 2-channel amp is to power one or two subwoofers.

Q: How do I bridge a 4-channel amp?

Run speaker wire from the positive terminal on channel one to the positive channel, and then run the wire from the negative terminal on channel two to the negative terminal. Do the same thing for channels three and four.

Our Top Pick

Our top pick is the Alpine 4-Channel Car Amplifier. It’s very versatile and can be powered using either two, three, or four channels, depending on its purpose. It’s compact, affordable, and delivers clean and precise power. The amp comes from one of the most respected brands in the audio industry and is very powerful for the price.

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