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Willie Greer
Are you tired of poor sound quality and your car speakers struggling without enough power? If this sounds like you, then a 4-channel amplifier is the answer to your problems. Unfortunately, a noticeable upgrade isn’t possible if you don’t pick the right one. That’s where our sound experts come in with some of the top 4-channel amplifiers out there.
SFB-200.4D
- Digital multi-channel design
- Variable high and low pass filter
- Variable bass boost
- 4-way protection circuit
RP-75.4AB
- MOSFET 4-channel amp
- Adjustable controls
- 4-way protection circuitry
- Thick metal outer shell
AMP1604
- Affordable price
- Full-range amplifier
- 1600 max power output
- 0.05% harmonic distortion
Reviews of the Top 4-Channel Amps
Skar Audio RP-75.4AB
The Skar Audio 4-channel amplifier is built to look sleek and last for years. Depending on the impedance rating, the RP-75.4AB can pump out 75 watts of power at 4 ohms and 125 watts per channel at 2 ohms. That’s a lot of power for a long playing time.
The thick metal outer shell of the Skar Audio 4-channel amp has built-in heat sinks to keep the amplifier cool while it handles the power loads. The Skar Audio RP-75.4AB is classified as an AB amp, and it gives users maximum control with adjustable gains, variable high pass and low pass filters, as well as a bass EQ switch.
What We Like
- Built-in heat sinks
- Thick and durable outer shell
- Adjustable gains
- High pass filter
- Low pass filter
- Bass EQ switch
- 105 dB signal to noise
- 125 RMS x 4 at 2 ohms
- 75 RMS x 4 at 4 ohms
What We Don’t Like
- Works better at 4 ohms
- The remote is not the best
Sundown Audio SFB-200.4D
The Sundown Audio SFB-200.4D gives users the choice to switch from 1 or 2 to 4 ohms. At 1 ohm, you get stunning power at 230 watts per channel. The number decreases to 148 watts at 2 ohms and 88 watts RMS x 4 channels.
The 4-channel amp provides a very decent frequency response with a signal-to-noise ratio of 100db. There are also both variable low and high pass filters in the SFB-200.4D with bass boost available.
The amp has a smart cooler fan that will keep the unit cool and operating for longer hours.
What We Like
- Variable high pass filter
- Variable low pass filter
- Smart Cooler
- 4 protection circuitry
- 100dB signal to noise ratio
- Clipping indicator
- 1 ohm is 200w RMS x 4
- 2 ohms is 125w RMS x 4
- 4 ohms is 75w RMS x 4
What We Don’t Like
- More expensive than some other models
- Not as sleek
Blaupunkt AMP1604
The Blaupunkt AMP1604 is a full-range 4-channel car amplifier with a max output power rating of 1600 watts. The difference between a full-range amp is the option to also run your subwoofer through it. You can control the amount of bass you want to go through the unit and pair with your speakers.
The class AB 4-channel amp has a signal-to-noise ratio of 96dB plus gain adjustment. Blaupunkt has committed to bringing you the best sound quality possible with a total harmonic distortion of only 0.05%. Regardless of the volume and power, this 4-channel car amp can bring the thunder.
What We Like
- Class AB 4-channel amp
- Signal to noise of 96dB
- Minimal harmonic distortion
- Full-range car amps
- Gives a significant boost to your sound system
- High output power
- 4 ohms and 2 ohms available
What We Don’t Like
- Deeper mounting brackets
- Ohms may fluctuate
Alpine MRV-F300
One of the most desirable traits about the Alpine MRV-F300 is it’s a great class D amplifier.
It has a 75w RMS per channel or 50 RMS per channel, depending on the impedance. As you can see, the Alpine MRV-F300 delivers the same power as larger models only in a 40% smaller chassis.
The installation is also a breeze, and users won’t experience any clipping or harmonic distortion. It’s a well-built amp that comes at half the cost of some of the more expensive models that may not bring as much power boost to the forefront.
What We Like
- 40% smaller chassis
- Class D amplifier
- 75 watts x 4 or 50 RMS watts x 4
- 2 ohms or 4 ohms
- One of the best amps for size
- Snap-on terminal covers
- Easy installation
What We Don’t Like
- Would be better with fork terminals
- 4-gauge cables will fit quite snug
Kenwood KAC-M3004
The Kenwood KAC-M3004 has an RMS power output of 50 w x 4 for 4 ohms and 75 w x 4 for 2 ohms. The total peak power is 600 watts, which isn’t bad for most vehicles. The Kenwood KAC-M3004 also has a nifty and convenient feature in a signal-sensing turn-on function.
The compact 4-channel car amplifier can receive signals from almost any source, including RCA cables or regular speaker wires. The amp eliminates the need for a remote due to the auto turn-on function, which also adds to the ease of use.
What We Like
- High compatibility
- Signal-sensing turn on function
- No remote needed
- Easy to use and install
- Class D amp
- Compact 4 channel digital amplifier
- Speaker level inputs
- 4 ohms and 2 ohms available
What We Don’t Like
- No airflow
- May get a bit warm
MTX Audio THUNDER75.4
A class A/B amp, the MTX Audio THUNDER 75.4 comes with variable LPF and HPF with 400 watts in total. Although it is a 4-channel amp, the THUNDER75.4 can be put into 2-channel or 3-channel mode, which significantly increases your car audio options. You can connect subs at a higher power or pair two speakers with a sub.
The crossover filters on the MTX Audio 4-channel amp also increase user control over sound adjustments to suit your setup. For mid-range speakers, the THUNDER75.4 features many crossover points for tuning to help the filters provide crisp and clean sound quality.
What We Like
- Can be switched to 2 or 3 channels
- Crossover filters
- Variable filters
- 200 watts RMS x 2 at four ohms bridged
- Class A/B amp
- Preamp inputs
- 2-year warranty
What We Don’t Like
- May experience minimal clipping at very high volumes
- Not the best for motorcycles
CerwinVega Mobile CVP1200.4D
Installation is a key motivator for many consumers, and the Cerwin-Vega Mobile CVP1200.4D is very easy to integrate into your sound system. It delivers high-quality sound within a decent price range and can provide clean and accurate bass for your sound system.
The 4-channel class D amplifier can give you 150 watts RMS x 4 at 2 ohms or 75 watts RMS x 4 at 4 ohms. This brings the total RMS power output to 600 watts and a peak power of 1200 watts – that’s a whole lot of power. The car amplifier is 4 ohms bridged and offers protection circuitry to benefit your car stereo system.
What We Like
- Full-range operation 4-channel car amp
- High and low level input
- High, low, and subsonic crossovers
- Protection circuitry
- Class D amp
- High power output
- Great price
- Very easy to install
- 2 ohms and 4 ohms available
What We Don’t Like
- May get a little warm
- Not as sleek
Audiopipe APCL2004
The Audiopipe APCL2004 is a 4-channel amp that delivers one of the highest power outputs our sound engineers have seen in a car amplifier. The power rating of 2000 watts total does not compromise its sound quality even at higher volumes.
The 4-channel car amp has a variable bass boost to let you control the low tones and can switch to 2-channel operation if it suits you. There are also low, high, and subsonic filters and protection circuitry that will keep your system safe from overloads and short-circuiting.
You can feel at ease using the 4-channel car amplifier for long hours thanks to the aluminum alloy heat sink.
What We Like
- Four ohms bridged
- High max power output
- 2 or 4-channel operation
- High level inputs
- 100 RMS w x 4 at 4 ohms
- 150 w RMS x 4 at 2 ohms
- High, low, and subsonic filters
- Aluminum alloy heat sink
- Protection circuitry
What We Don’t Like
- Can have a bit of fan noise
- You have to make sure the unit is clean to eliminate noise
BOSS Audio Systems PF1800
The BOSS Audio Systems PF1800 has a class A/B topology. As the PF1800 is a full-range amplifier, it means you can run speakers and subwoofers through it. It has a MOSFET power supply, which means it has a switch that controls the voltage precisely and eliminates secondary feedback circuitry.
As for the sound quality, the PF1800 from BOSS Audio systems has a variable gain control and bass boost. These functions allow you to control how much bass and how much signal you want.
This 4-channel car amplifier is a bridgeable design, which means you can connect amplifier channels.
What We Like
- 450 watts x 4 at 2 ohms
- 900 watts x 2 bridged at 4 ohms
- Full-range for speakers and subwoofers
- Speaker level and low level inputs
- Bass boost and gain control
- Protection circuitry
- MOSFET power supply
- Class AB amps
What We Don’t Like
- The wattage may not always reach peak
- Can do with better heat dissipation
4-Channel Amps Buyer’s Guide
There are a few key factors to look for in order to ensure you get the finest 4-channel amp you can get for the money. Not all of them are built the same, nor will they all give you the same sound quality. If you follow our professional sound engineering team’s advice, you will take home an excellent product that will address all your power boost needs.
Size
The size of the 4-channel amp depends on the amount of space you have to accommodate it. There are plenty of small and compact options on the market, many of which have made it on our team’s list. The most wanted 4-channel amps will definitely be compact and lightweight to minimize clutter.
Not only will a small footprint open up a lot of placement options, but older models that were cumbersome and heavy needed much more room to dissipate the heat they generated. This means they needed to be placed somewhere with open space. These heftier units also didn’t possess the best cooling systems, which affected their longevity.
Luckily, our experts say we live in a technologically advanced age where units are getting slimmer, smaller, and more compact. If you opt for a smaller 4-channel amp, you will be able to place it under your car seat and still provide enough room for it to vent high temperatures.
The size will also impact the design of the amp. A major discrepancy between low quality and a high-quality amp is in the finer details. Better amps usually come with more desirable surface mount technology, which means the amp may be more compact.
The components and materials used to build the amp will also be more durable and wear-resistant. Notice how our sound engineers said better amps, but not pricier amps. While price and quality may go hand-in-hand for many products, it isn’t always the case for technology.
It’s very possible to find an exceptional amp for around 100. Of course, you can choose to spend more on certain brand names. Another variable that sets big brands apart from the lesser-known ones is the resources they are privy to. They will understand how to construct the best 4-channel amp that is designed to create better sound and not only use higher quality components and hope for the best.
Speaking of size, you should also take a look at how big or small the amp fuse is. The amp fuse dictates whether the 4-channel amplifier can handle the amount of power it claims to deliver.
Our experts tend to lean more towards a modern smaller amp because placing it under your seat and not having to worry about it sounds better than having to make a special place for your amp.
Power Rating
Unlike speakers and subs, the power rating for a good quality 4-channel amplifier is listed in watts RMS, so what you see is what you get (for the most part). You will also see the max power, but the RMS is what they tend to market, which is great because our sound engineers say it’s the one to pay attention to.
The watts RMS in amps refers to how much wattage can be pushed through per channel. In the case of 4-channel amplifiers, we often see it listed times 4. The wattage for your amps will also vary depending on the impedance. The peak power is the total wattage of what’s pushed through all channels added together.
As said, the wattage output of your speakers will depend on the impedance. For example, if you have a 400w RMS rating for 2 ohms, that number will no longer be 400w RMS with 4-ohms impedance. Generally speaking, the higher the impedance, the lower the watts per channel.
Our experts say 100w RMS power per channel is a pretty decent power rating. Keep in mind that 4 ohms and 2 ohms will have varying power outputs, with 4 ohms usually lower than 2 ohms. If you have 100w RMS for two ohms, that figure will most likely be lower for 4 ohms, and that figure may not be enough for some vehicles.
It’s important to consider the power rating for the ohms you want because it could make a very significant difference to the sound quality plus power supply.
There are also special amps, a few mentioned above, that can be switched from 4-channel amps to 2 or 3-channel amps. Of course, the wattage output will change depending on the channels you choose.
It’s important not to push your amps to the brink often because it could compromise the sound quality. You may hear clipping sounds in your speakers, noticeable distortion, and even damage to your amp, speakers, and subwoofers.
One extra tip our team members have for our readers is to look for amps with quality certifications. The CEA or Consumer Electronics Association [1] was established as a standard for testing the power ratings. You may see other consumers give poor reviews for some devices because of false power rating claims.
Just because something was advertised to put out a certain wattage doesn’t mean it always can. If the unit you are looking at has earned the CEA’s seal of approval, you get the power ratings advertised without misrepresentation.
Amp Class
The amp class or topology of the amps is basically the architectural technology of the amp. There are 4 classes, but we most commonly see class AB and D amps. Our experts say that the AB amp class can generally produce better sound quality, but class Ds don’t generate as much heat because they are more efficient.
As far as the sound quality, our team says there will barely be a noticeable difference, even for avid audiophiles. Class Ds don’t do as well for high notes, but again, the variance is negligible.
The biggest discrepancy between the two types that still applies to modern amps today is just the efficiency and heat. ABs can run much hotter, so if you are looking at a class AB amp, it’s important to acknowledge the cooling systems that accompany it.
Another generalization our sound engineers have for you is that AB amps are usually larger and heavier as well. This is necessary because they need a more durable enclosure to help dispel the high temperatures. You will notice that a smaller and more compact 4-channel amplifier will be classified as class D.
You may not always have a choice when it comes to the amp class, especially since a part of it is the impact on the profile. If you have a small vehicle, you may only be able to work with a Class D amp. Yes, you may have to compromise on the quality of some things, such as the high notes in certain speakers, but you do gain power efficiency.
Frequency Response
You may find it curious that an amp also has a frequency response since it doesn’t produce sound directly, unlike speakers. The frequency response in an amp refers to the range it can deliver to your connected devices. As our expert techs have said many times before, the human audible range is within the scope of 20Hz to 20kHz, so you don’t really need more than that.
You will notice that some 4-channel amp units will have subsonic crossovers, and you may also wonder what the purpose is. We will talk about that in more detail in a bit, but the subsonic frequencies are ones that are so low that the human ear can’t detect them, but we can still feel them. Supersonics are frequencies that are way too high for us to hear.
You don’t have to have a 4-channel amp head into these ranges to bring the best sound quality, but our experts recommend at least having your amp push what we can hear within the 20Hz to 20kHz.
Total Harmonic Distortion
The total harmonic distortion will do a number on your sound system. Ideally, our team wouldn’t want any harmonic distortion, or at least any detectable one.
The total harmonic distortion, or THD for short, refers to how precise your 4-channel amp is at mimicking the input signal. The lower the number, the better, and we have a few options on our list barely even making 0.05% THD.
The total harmonic distortion is a great way to assess the quality of a four-channel amp at a glance. If you have a high THD rating, then our experts urge you to take your money elsewhere. A four-channel amp should have less than 1% of total harmonic distortion.
What is too much THD? Our team says no matter the power rating or volume, definitely steer clear of an amplifier with more than 1% of harmonic distortion if you can help it. If it exceeds 3%, then that is a major red flag because the sound quality will be laughable at enhanced volumes.
SNR
Another feature that is crucial in a four-channel amp is the SNR or Signal Noise Ratio. The S/N ratio pertains to how much noise is carried over through your 4-channel amp. Basically, it’s the sound signal to noise signal. The figure is measured in decibels, and like with speakers, the higher the decibel, the better.
Similar to speakers, our team suggests looking at ones over 90 at the very least, but if you can find a 4-channel amplifier that can exceed 100, then that’s a great unit to invest in.
Unfortunately, background noise is a constant within an amplifier. It’s an audible hiss that you may hear regardless of whether your speakers are turned on. The noise is even clearer if the gain setting on the amplifier is turned on, so you can attempt to keep it at a minimum if possible.
Keep in mind that the S/N ratio is just a general estimate, and manufacturers can sometimes inflate these ratings. In which case, our professional team suggests looking for an amplifier with the highest rating possible so the results won’t be as different.
Crossovers
Since we do live in technologically advanced age, the crossovers in an amp are usually built-in, unlike the amp models of old. The most coveted 4-channel amp will definitely have crossovers built-in.
The crossovers in speakers have a prominent role in the sound quality of your car audio system. Plus, the crossover will also ensure the best sound quality out of your car stereo system without distortion.
A crossover is key when pairing with coaxial speakers because it just doesn’t do very well with the lower frequencies. Even dedicated component speakers can do well with an amp. Many of the tunes we love have deep rumbling bass that can’t be properly portrayed, which will lead to distortion at high volumes.
A 4-channel amp does best with high pass crossovers but definitely look for ones with low-pass crossovers as well for subs. The crossovers in many of the top 4-channel amps our experts have seen feature variable crossovers, but there are ones that are fixed.
If you are someone who likes sound customizability, look for ones that can be adjusted. Bass boosts in a 4-channel amp will also bring another layer of excellence to the sound quality of your car stereo system.
Compatibility
Another key consideration and perhaps the most important one for the best 4-channel amps is compatibility. You need to make sure your 4-channel amplifier works well with the rest of your system, including your head unit.
You have to look at the inputs to determine whether or not the 4-channel amp of your choice is compatible with the head unit. Car amps can have RCA or speaker level inputs. Unfortunately, most factory head unit models do not have RCA.
Check to see if your speaker can receive a speaker level signal. If so, then the receiver won’t matter as much.
There are also some units that are only able to receive pre-amp signals. If this is the case for you, then you will need a line-out. The line-out converter changes the speaker level signal into one that is compatible with the RCA.
(If you do not have the RCA input, you can check this simple guide about connecting an amplifier without RCA jacks)
Filters
Our experts also brought up filters in many of the amp models above, regardless of class. The filters have a huge role to play in the quality of the sound. There are both high pass and low pass options with a typical car amplifier.
Most car amplifiers of decent quality will have at least the two former ones. The third filter is meant for more specialized purposes. For the average listener, our experts say the HPF and LPF are all you need to boost amplifier performance.
HP filters will allow frequencies of the same name through, while low pass ones will send midbass to subwoofer frequencies through. There are car amplifiers with the HPF that can also work with the tweeters and super tweeters, but they are usually found in higher-quality amps.
Extra Features
In this section, our team will go into more detail about how class AB or D amplifiers can help boost the sound quality of your speakers.
Adjustability is a vital function for an amplifier to provide for you to customize your listening experience. For example, you can find adjustable equalizers, which allow you to filter different frequencies to your speakers. In both a class AB and D 4-channel amplifier, this is usually automatic. However, our experts prize ones that can be customized.
Is there a remote control? It’s great if your amplifier comes with an automatic sensor turn-on for speaker level inputs, but some do not. If your amplifier needs to be switched on manually, then it will most likely include a remote control that could also let you adjust the sound.
What is a 4-Channel Amp?
A 4-channel amp is an amplifier that boosts your electrical signal to 4 different channels. They can also provide extra features such as bass boosts and built-in crossovers for a few of your channels.
Some 4-channel amp models may also allow a process called bridging. This is when you can combine the power of more than one channel to boost the output. Why boost the output? You may need to do it to improve the sound quality of a certain speaker’s output.
In a situation where one speaker requires more power, your amplifier is versatile enough to accommodate by allowing you to “bridge” two channels into one. More often than not, you will exactly double the amp’s output. Unfortunately, this is only the case if you have a decent-quality amplifier.
Bridging a 4-Channel Amp
As said, bridging a 4-channel amp can boost your power output and sound quality. In a better 4-channel amplifier, you can reach double the amount of power compared to before. You can bridge your 4-channel amplifier manually, and it’s not very difficult.
4-channel amps will feature 4 speaker terminals. There will be both positive and negative terminals present, which gives you a total of 8. The panel will be located on one side of the amp, so it won’t be difficult to find.
Take the speaker wire and plug one end into the positive terminal of the first channel and the other to the sub. This next part is where it can get a bit tricky.
Grab a pair of wire strippers to cut out about 3 inches of insulation from either side of the wire. Then place it into the APP terminal. It’s best to use a screwdriver here to help you out for precision and safety.
The next step is to do the same thing but run the wire from the negative speaker terminal to the negative subwoofer terminal. Then clamp down the wire by removing insulation and screw down the wire securely. Do the same for the next two channels. The third speaker terminal should also go from positive to positive for the second sub, and the fourth terminal is negative to negative.
(Looking for the perfect gadget for your car? Why not try getting great Android car stereo we recommended here)
FAQ
Who makes the best 4-channel amp?
Skar Audio makes the best 4-channel amp. Not only is the Skar Audio RP-75.4AB within a great price range, but it is also an A/B class amp with MOSFET and user-adjustable controls. There is also a 4-way protection circuitry built in these amps to ensure no overloads.
How many speakers can a 4-channel amp power?
A 4-channel amp can power up to 8 speakers. Most of these car amps can power more than one speaker per channel. Even though 4-channel amps can easily power up to 8 speakers, it’s not recommended due to the high toll it takes on your amp.
What's better 2-channel or 4-channel amp?
A 4-channel amp is better for front to rear sound. A 4-channel will allow for more overall control and be able to power more speakers. Opt for a 2-channel amplifier if you have a no-frill car audio system, and all you need is to boost a single pair of speakers.
Our Top Pick For a 4-Channel Amp:
Skar Audio RP-75.4AB
The Skar Audio RP-75.4AB takes the crown as the best amp with 4 channels. It has an amazing power output at both 2 ohms or 4 ohms impedance. Additionally, the Skar amplifier gives users a lot of control over the filters, gain, and bass EQ. The 4-way protection circuitry will keep your car audio system safe from short circuits and overloads.
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