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Best 4 Channel Amplifier for Optimal Sound Quality

Boost your car stereo sound with a new 4 channel amp.

Best Overall Choice

MTX Audio THUNDER75.4 Thunder Series Car Amplifier

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Best Budget Choice

Kenwood KAC-M3004 Compact 4 Channel Digital Amplifier

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Best Premium Choice

Rockford Fosgate P600X4 Punch 4-Channel Amplifier

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car stereo

If your car stereo amplifier doesn’t sound good enough for you and you currently use front and rear speakers, then a 4 channel car amplifier might help. Investing in a decent 4 channel car audio amplifier is an ideal way to produce a nice full range, premium sound quality from your speakers. It also works well if you currently have a two speaker and subwoofer setup.

The trouble is that most people don’t know what to look for in a high-quality power amplifier. That’s why we’ve set up this complete 4-channel amp buying guide and list of our favorite options on the market. Choose one of the amps listed below and you won’t believe the difference in your sound system.

What is a 4-Channel Amp?

Your 4 channel amplifier is very much the same as a 2 channel amp but there are a few differences. They both contain a power supply to heighten the 12V battery voltage. Without this, the speakers wouldn’t receive enough output power to operate correctly.

A 4 channel amp utilizes four independent amplifier sections and signal paths instead of two. Many of them also have a 2/4 channel input switch. This works well when you connect to a head unit that has two channels available so you can drive four channels of power.

Many of the 4 channel amps today are also bridgeable. This means they can be connected to a single speaker load from two channels to offer more power. They’ll also provide options like crossovers or bass boost for two of your four channels.

2 channel amps are best used to power a subwoofer. That’s why it’s not uncommon to see both the 4 channel and 2 channel amps in use at the same time in a sound system. The 4 channel amp powers the car speakers while the 2 channel amp powers the subwoofer.

Picking the Best 4 Channel Amp

When you’re shopping around for a 4-channel amp, there are some things you’ll want to be aware of.

Signal-to-noise Ratio (SNR)

You’ll find this rated in decibels. What you want to see is a low amount of noise compared to your audio signal. If you find a 4 channel car amp with great sound quality, it would feature 90dB or higher. The top-of-the-line is going to have 100dB or higher. While background noise occurs in most amplifiers, you don’t want to hear it easily.

Sometimes a manufacturer exaggerates their specs and you end up with more SNR than you anticipated. That’s why it’s vital to read the reviews before making a purchase.

Crossovers and Options

If you want the best sound, you need to invest in an amp that offers superior crossover features. If the speakers can’t handle certain frequencies or are driven to distortion, it doesn’t matter what you spend on your amp; the sound system will be poor. Have the use of crossovers dramatically impacts the quality of sound your speakers produce.

Most crossovers allow you to receive more volume minus the distortion. With these, you’ll achieve better sound quality and clarity.

Smaller component speakers won’t produce the lower-end bass as a subwoofer does. When you play your favorite tunes, you’ll hear distortion as a result. With the best 4 channel amp, you’ll achieve full-range sound from your speakers.

You’ll also want to consider an option with fixed cutoff frequencies. That’s the frequency where sound below or above is blocked. A fixed one is normally set at 50 to 60Hz which works well. You may also find a 4 channel amplifier with the bass boost feature which helps if you don’t currently have decent sound controls with your stereo.


The best sounding amps utilize well-designed circuit boards that have been planned out carefully. These boards feature high-quality components which add better sound to your system. You don’t want a company that takes manufacturing shortcuts.

Surprisingly, you’ll find a substantial difference in the lower quality amps versus a high-quality design. That’s because in a cheap 4 channel amp, the small details were overlooked in order to keep the production costs down.

Car amps that produce the best sound often have these things in common:

  • Thicker and better-printed circuit boards, otherwise known as PCBs
  • High-quality components
  • Surface-mount technology (SMT) parts which shorten paths
  • Low-noise proprietary circuits and parts which heighten the sound quality

Thankfully, you don’t need to invest a lot of money to achieve these qualities. Some on the market for less than $200 offer this type of quality. If you choose a well-known brand, you know they’ve invested money in the research of their product. A no-name brand, on the other hand, doesn’t have that money to spend, and they’re just looking to make a quick profit.

CEA Logo

cea logoThese compliance standards exist to help consumers weed through the misleading and confusing advertising ratings that stereo manufacturers use. These offer clear ratings and defined specs to make comparison shopping even easier.

If an amp features the CEA-2006 compliance, that means they aren’t employing any advertising gimmick and won’t misrepresent their power ratings.


To produce the best sound, you need the right amount of power. That’s why it’s recommended to choose a 4 channel amp that features a minimum of 50W RMS per channel. If you like to go loud, then 75W RMS might work better for you.

Class D Car Amps

Chances are you’re going to notice Class D car audio amplifier models while shopping, so it’s important to know what they are before you spend your money on them. This new line of technology is efficient, take up less space, produce less heat, require smaller power wires, and draw less power overall.

One of the drawbacks to this style is a higher noise level. That’s why it’s essential to purchase the highest quality amp you can afford to get the filtering and circuitry needed to reduce this noise.

A Class AB design is cheaper because they’re easier to produce. These are the recommended choice if you need to get a decent sound and stick to a budget.

Top Ten 4 Channel Amplifiers Reviewed

We’ve compiled a list of the best 4 channel amps currently on the market. In this list, you’ll find a wide variety of budget options and features available. This allows everyone to find a unit that works best for their stereo setup.

Best Overall Choice

1. MTX Audio THUNDER75.4 Thunder Series Car Amplifier

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With MTX Audio, you tap into the legendary power and build quality. This amp fits into a small space and is quite affordable as well. With this clever design, the manufacturer squeezes a lot of power into the amp. Because of the surface mount technology (SMT), there are shorter paths for the audio to take which leads to less vibration. It also comes with short-circuit, DC offset, and thermal protection to protect your amp from trouble.

This compact, hard-hitting, basic amp is well-made and doesn’t compromise your sound quality. It’s also easy to install and offers some great crossover features. The high-pass is adjustable up to 750Hz, while the low-pass can be adjusted to 200Hz.

This isn’t going to give you extreme levels of sound quality; it just isn’t that kind of amp. But, if you desire to get good sound without breaking the bank, this is the way to go.

2. Alpine MRV-F300 4-Channel Car Amplifier, 50 Watts RMS x 4

Alpine MRV-F300 4-Channel Car Amplifier

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This is one of the smallest 4 channel amps you can purchase right now. It’s nice looking as well with the metal finished plus blue power indicator. There are even optional end caps which offer a cleaner installation. With a flush-mount custom install, this would be ideal.

It’s rated at 50W x 4 RMS @ 4 Ohms or 75W x 4 RMS @ 2 Ohms. It’s also bridgeable into 150 W x 2 RMS @ 4 Ohms. It also features an adjustable high/low pass plus a bass boost. You’ll have a hard time finding another amp with this quality for such a low price.

3. Alpine KTP-445U Universal Power Pack Amplifier

Alpine KTP-445U

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We’ve decided to include this model from Alpine as well even though it doesn’t come with the same quality specs of the other amps on our list. That’s because some people just need to stick to a budget, but want the best sound they can get. When that’s the case, you can’t go wrong with this model.

This compact amp uses some high-tech engineering to produce a decent sound quality without draining your bank account. This class D amp never runs hot and offers 45W RMS to four channels. It’s also bridgeable to 90W RMS for two channels.

One of the best qualities is that it provides RCA and speaker level inputs. That’s what allows it to work well with both aftermarket and factory car stereo systems. With the 2/4 channel switch, you can also utilize it when you only have two RCA jacks instead of four.

4. Rockford Fosgate P400X4 Punch 4-Channel Amplifier

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If you need more power, then you’ll want to check out this option from Rockford Fosgate. You get the legendary and high-powered MTX Audio quality in a compact size that remains affordable. This amp squeezes in a lot of power for the maximum punch.

That’s because of the short audio paths and vibration resistance. There’s also protection for DC, offset, thermal, and short-circuit components to protect you from any issues.

This A/B amp is proven to work well and even comes with some patented designs. The crossover features are also user-friendly and make getting the sound you desire simple. On this model, however, there are no speaker-level inputs.

5. Rockford R300X4 Prime 4-Channel Amplifier

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The fact that we feature several amps from this brand should tell you something about the brand. This lower-end 4 channel amp isn’t going to give you as many features and high level of sound as the last one, but it’s great if you need to pay less.

With that said, there’s still lots of power for even a larger vehicle. You can run this in bridged or mono mode and the Butterworth crossover effectively filters out some high frequencies.

The best part about this option is that it won’t get hot as some other lower-priced models do. That’s because of the cast aluminum heatsink design which also extends the life of this amp.

6. Kenwood 1177524

Kenwood 1177524 Compact Automotive amp

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This is the first 4 channel amp that also offers Bluetooth application. With the popularity of playing music on mobile devices, it only makes sense to design an amp that’s Bluetooth compatible. On top of that, it’s compact and supplies a good amount of power. When its hooked into four speakers, it outputs 45W.

The design also features a coated board which resists moisture. In addition, the amp offers a signal sensing turn-on switch as well. You can think outside the box with this amp and install it on your motorcycle, ATV, RV, or boat for great sound quality anywhere you go. Not only is it small in size, but it doesn’t draw a lot of DC. Plus, the price can’t be beat.

7. Alpine MRV-F300 50 Watt 4 Channel Car Amplifier, RMS x 4

Alpine MRV-F300 4-Channel Car Amplifier

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This lightweight and compact amp provides great sound while sticking to a small design. In total, it generates up to 640W of power. In addition, you’ll find that it runs cool even after you’ve been using it for a long time. Alpine points to the anti-shutdown technology they utilize in the unit.

Another perk with this system is that it is easy to install. You won’t have to hook it to any external converters plus the terminal covers simply snap on. This Class D amp is 40% smaller than their previous model they put out. That’s a lot of space you’ll save, plus some extra money you’ll get to keep in your pocket as a result of purchasing this low-cost option.

Best Budget Choice

8. Kenwood KAC-M3004 Compact 4 Channel Digital Amplifier

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Speaking of low-cost 4 channel amps, this is one of the cheapest on our list. Kenwood is a respected brand in audio equipment, so there’s no reason not to trust them with your car stereo. This amp is easy to install and doesn’t require a lot of effort to start using.

The peak 600W power output satisfies most car owners and can be used with a three or four-speaker setup. It also features RMS power, voltage sensing auto-on switch, and full circuit protection. This amp weighs just over two pounds and is super compact. That makes it ideal for even the tiniest spaces.

In addition, the board is coated to resist corrosion and moisture. The downside to this option is that Kenwood only offers a one-year warranty, which is less than some other manufacturers. For the price, it’s hard to complain about that, though.

9. Pioneer GM-D8604 Class FD 4-Channel Bridgeable Amplifier

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Pioneer is another brand that makes affordable and high-quality stereo components. You’re going to receive decent sound from your front and rear speakers without investing a wad of cash. You also won’t have any trouble finding space for this design. It’s compact and lightweight as well.

This amp offers 100W per channel @ 4 ohms. With the newer circuit design, you’re also protected from any short circuits, low-voltage output, and power surges. If you prefer to pair the front speakers with a subwoofer, this amp is ideal. It’s bridgeable and easy to install. This allows you to have a versatile application for whatever your setup consists of.

Best Premium Choice

10. Rockford Fosgate P600X4 Punch 4-Channel Amplifier

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Of course, we had to throw this model into the mix. Yes, it is expensive, but you’ll find it’s worth every penny if you desire excellence from your car stereo. This puts out 125W per channel @ 2 ohms. It also includes an audio turn-on circuit that makes your wiring simple. Once the amp senses voltage, it fires itself on without you doing a thing.

Because of the aluminum heat sink that’s built-in, the amp also remains cool during use. There are some other safety features as well, such as short-circuit and overload protection. With the RCA pass-thru outputs, you’ll find installing a subwoofer to the amp is an easy task.

This is a heavier unit than everything else we reviewed. It’s also not very compact, but it’s going to provide your car stereo with the power and sound you deserve to enjoy. It’s an investment well needed if only the best will do.

Brian Jones
About Brian Jones

Brian Jones spent over 30-years at various dealerships as an ASE Certified Master Tech. These days he works with those dealerships to create quality automotive content while spending more time with his family near Dallas, TX. In his spare time, you'll still find him playing with tools, cars, and many other "manly" gadgets. Brian's passions include traveling, pickup trucks, and anything related to motorsports.