Buyers guide

The Best Car Amplifier (4 Channel) – Buyer’s Guide and 5 Excellent Choices

Let me go ahead and be completely honest – I love 4 channel amplifiers! As an installer and a car audio fanatic I’ve installed, tested, and tried many car amplifiers over the years and for my money a 4 channel amplifier has always given me the best bang for the buck. I love the flexibility they offer! But finding the best car amplifier with 4 channels can be tough! There are so many to choose from today.

That’s why I wrote this guide – to help you make a great decision and get one that will both let you build the system you want, but most importantly, that you’ll enjoy. After all, don’t you love how it feels to hear your favorite music, loud and clear? I do.

I’ll cover a lot of basic information here so you’ll have a great understanding of the differences from other types of amplifiers before buying. I’ve picked out 5 excellent models, along with a brief review of each, that will be great for nearly anyone and that I know you’ll be happy with.

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Car amplifier basic types: 4 channels vs. the others

4 channel amps are as you may have already guessed extremely similar to 2 and 5 channel models. They do share a few differences however. They too use a single power supply to provide a higher output voltage, stepped-up from 12V, to drive the speakers with more power than is possible with only 12V like factory systems.

Following this, they contain 4 independent audio amplifier sections which these days are normally designed in such a way that each channel pair can be bridged for additional power if desired. Some have features such as a bass boost control that may be used only for 2 of the 4. This varies from brand to brand and model to model, so it’s important to be sure before buying.

Internal image of a 4 ch. amp

A 4 channel amplifier is basically the same as a 2 channel amplifier and most can be bridged for more power. It’s important to note that some, however, do have special features (such as a bass boost option) available only on 2 of the 4. This class A/B amplifier shows many transistors on the left hand side: 16 total, with 4 per channel used to drive speakers. Hence one reason why it’s longer in size.

System flexibility and advantages

4 channel amps are very flexible and offer a number of advantages over other models. You can configure (and easily reconfigure) many different types of sound systems in your car.

For example:

  • A 4 speaker system (front/rear)
  • Front full-range (2 ch.) + bridged subwoofer
  • High pass/low pass component speaker setup, with tweeters on channels 1-2 and woofers on 3-4
  • Front speakers with a high-pass crossover and front woofers on low-pass channels

When adding a 2nd amp, the possibilities are even more extensive! Remember that it’s ok if you don’t use all channels present in an amp – there’s no harm in having a speaker output disconnected.

Basic features to look for in an amplifier

There are a number of basic features that although are very common in modern amplifiers you should always verify they’re present before purchasing, rather than assume.

I recommend an amplifier with built-in high and low-pass crossovers. Ideally these would be adjustable although that’s not a primary concern. But it does make it easier to tailor the sound to your liking and it’s especially true when using the high-pass feature to block lower end bass from speakers that can’t handle it in order to prevent distortion and get more clean high volume sound.

Ideally you’ll also have an amplifiers with good terminals which are easy to connect power and speaker wire too, but remain secure and well-connected after installation.

Understanding class A/B vs. class D

Technology has improved a lot in the last several years when it comes to car amplifiers. Although the traditional designs that have been around for decades, class A/B amps, still remain. Whereas as traditional A/B amplifiers are based of a design in which driving transistors largely remain on during use (even when no audio is present) and are only near 50% efficient, class D amplifiers are nearly 90% efficient and can be designed to fit into much smaller chassis. A class D amp works buy switching the transistors that create an audio waveform incredibly fast, saving energy and bringing heat levels down to an incredibly low level.

Class D amps do have one drawback: because of how they operate, the noise floor is somewhat higher than that of A/B amps, which you can hear as a slight hiss if you listen closely and especially if the gain is turned up high. It’s critical to buy a well-designed brand name amp to get the best sound and lowest noise as lower-end amps aren’t as well designed. Today’s brand name 4 channel class D amps have reduced noise levels and generally overall better sound than others, and proven by the many happy customers who’ve said the same.

Class A amps are low-noise designs somewhat similar to A/B, but even less efficient and generally not as common. They’ve often much more expensive, to.

Image of Alpine KPA-445U mini amplifier controls

Class D amps use relatively recent design to produce efficient power and can be incredibly compact as they don’t waste large amounts of energy as heat like older amplifiers. This Alpine KTP-445U 45W x 4 mini-amp, for example, measures only 7 7/16″ x 1.5″ x 2.5″ (189 x 38.2 x 64.5 mm) in size!

Why choosing a class D may be the best choice

Because they’re so small, this type of amplifiers opens new possibilities for installation and can fit in areas previously completely unavailable! That’s a fantastic advantage as you can do things like the following:

  • Place an amplifier under a seat (or 2 for a multi-amp system)
  • Install them in storage containers in your vehicle’s interior
  • For trucks, they can be placed under the normally limited space under the rear folding seat
  • Hide them from thieves looking in your vehicle to avoid theft

Quick Tip
Because they’re so efficient you can actually get away with smaller size power wire. Remember that while they have great power output, very similar to traditional amps, they don’t turn nearly have of the electrical current entering them into heat, so they draw far less current.

However is having the lowest noise level possible is a concern for you, then perhaps A/B is the best choice. I’ll list some models below that are great choices.

How much power do I need?

As an installer I generally recommend a minimum of 50W RMS per channel into 4 ohms. If you’ll be driving subwoofers and are likely to want very heavy, high-powered bass you should select a model with much higher bridged power instead.

For most people a 50W RMS x 4 amplifier is fine, as it provides sufficient volume and bridging the amp generally provides around 150W into 4 ohms, which is sufficient to drive a subwoofer well for great bass sound.

For great sound with additional high-volume ability, I would choose a 75W per channel or higher model.

★ The best 4 channel car amplifier for your money ★

5 excellent choices

#1 Alpine FRV-F300 – Great sound in a small package…a fantastic choice for most

Image of MRV-F300 amplifier endImage of MRV-F300 amplifier end - controls side

This is one of the most compact and best sounding 4 channel car amps today. It features end caps that snap on and off for a cleaner-looking installation, great sound, 50W x 4 (4 ohm) / 75W x 4 (2 ohm) power, and is the next evolution in car class D technology. It measures only 7 7/8″ W x 6.5″ D x 2 3/16″ H (200 x 165 x 55 mm) and is so small it easily fits under seats too. It’s bridgeable to 150W into 4 ohms.

Alpine has done additional engineering work to reduce noise in the model, and it shows…or should I say it can be heard! Few class D amps can say the same.

Full crossovers as expected and a bass boost is available on channels 3/4 as well. Speaker level inputs are provided, too, in case you have a factory system you’re looking to upgrade. I’m so impressed with it that I did a full review you can read here. This is a fantastic and great sounding powerhouse you shouldn’t miss! It sells for close to $150, depending on the retailer.

It’s a very cool amp that’s affordable, so definitely check it out over at Amazon. The price is pretty low there and there are lots of customer reviews to help you feel confident in your decision.

#2 Rockford Fosgate Punch P400X4 – Powerful, all-out fantastic sound and better features

Punch P400X4 top view

Punch P400X4 controls view

If your budget allows you to spend a little more, the P400X4 is one of the best on the market today. Rockford Fosgate has used class A/B design with their own Trans-ANA circuitry to deliver lower noise and some of the best sound quality available in this price range (around $200).

The company’s legendary expertise in car audio design makes it possible to get all of this in an 11-1/8″W x 2-7/16″H x 8-13/16″D
inch size. That’s because the company uses the latest and best electronic components available –not the cheapest like competitors!

The high and low pass crossovers are adjustable to 250Hz, while the Punch EQ2 is unique from other brands in that it’s adjustable for both bass and treble with 0-18 dB level possible at 45Hz and 12.5KHz. A Punch EQ remote control knob (sold separately) can be added for adjusting the sound while driving. It doesn’t support speaker level inputs, but a 2/4 way input switch is provided for the RCA inputs.

What I really love – and what definitely sets it aside from others, is the C.L.E.A.N. gain setup system feature which, when used with the included test tone CD, actually allows the amp to indicate signal levels to aid in setting up the amp gain. It allows you to the lowest-noise and best optimization for your amp.

The amp is conservatively rated (will actually exceed its rated specs) at 50W x 4 into 4 ohms (100W x 4 into 2 ohms) and 200W x 2 when bridged to 4 ohms. A certificate of performance verification is included, too!

You’re much better off buying it from Amazon as other retailers seem to be quite a bit more expensive for the same item.

#4 MTX Audio Thunder 75.4 – More power in a smaller size than other A/B amps

MTX Thunder 75.4 side view MTX Thunder 75.4 end 1

If you’re wanting the absolute lowest noise in your music but still want something affordable, the Thunder 75.4 can give you that – and more power in a smaller package than other similar amps!

MTX has managed to fit 75W x 4 (@ 4 ohm) channels of crisp, powerful musical reproduction into a package that’s only 12-5/8″W x 2-1/4″H x 6-5/16″D in size thanks to using surface mount technology (SMT). It can also deliver 100W x 4 @ 2 ohms and 200W x 2 bridged to 4 ohms.

The high-pass crossover is adjustable and reaches as high as 750Hz while the low pass is adjustable to 200Hz. 4 gauge-capable power connection terminals and well-made, secure speaker wire terminals round out a great design you’ll love. However it doesn’t provide speaker level inputs.

It’s a fantastic and powerful compromise between cost, size, and power, selling for less than $200.

Head over to check out the fantastic reviews and current price at Amazon now.

#4 Alpine KTP-445U Mini Amplifier – A great sounding and high quality amp that can fit nearly anywhere

Image of Alpine KPA-445U included itemsImage of Alpine KPA-445U mini amplifier controls


As I wrote about in my extensive review, the KTP-445U is a marvel of Alpine’s expertise in compact audio based on class D technology. As not all of us have room for a standard sized amplifier (even the compact ones listed here) it solves the problem of having very limited installation space while still providing up to 45W of clean sounding power into 4 channels! And it even handles 2 ohm speaker loads.

The amp measures an astounding 7 7/16″ x 1.5″ x 2.5″ (189 x 38.2 x 64.5 mm) in size. That’s smaller than pretty much any comparable amplifier available anywhere in the world today! It can be installed using the included brackets or even using zip ties if you are working with a more difficult installation challenge, like putting it inside a dash.

Even better is that it features built-in high and low-pass crossovers which are enabled by switches on the bottom. You can also use all 4 channels with only a 2-channel input source thanks the the built-in “Y” adapter function. Both RCA and speaker-level inputs are provided.

Alpine has taken great care with a fresh design of their own in order to minimize noise and keep the sound quality great, responsive, and crisp, with excellent high-end response you’ll love. It sells for somewhere around $160.

Head over to check out the amazing reviews from others and the best price at Amazon now.

#5 Planet Audio Anarchy AC1200.4 – A good budget buy that doesn’t skimp on power

PLanet Audio AC1200.4 amp top

PLanet Audio AC1200.4 amp side



Have less than $100 to spend? You’re in luck, as you can still get a good buy and plenty of good, powerful musical sound that’s easy to use and looks good too. It can also be used with factory speaker level systems. Thanks to the AB traditional design you can spend less and still get better sound quality than some of the low-end competing products out there today.

Power is 113W RMS x 4 into 4 ohms (225W x 4 into 2 ohms) and bridged 450W x 2 into 4 ohms. It features high/low pass 12dB crossovers and an adjustable 0-18dB bass boost on channels 3/4. It also has thermal and speaker short protection circuitry.

The Planet Audio amp shares the same basic design as the parent Boss company brand, just so you know. It’s not on the level of the models I’ve listed above, but offers decent quality and isn’t short on having enough power to let you enjoy a great system in your vehicle.

You can check out the current price and the many happy reviews here at Amazon. It’s a good deal all around.

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