Best 4 Channel Amp

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We’ve reviewed a lot of speakers lately and you’ve been asking us about amplifying speakers. It is time for us to deliver.

We’ve tested the best 4 channel amp from every tier 1 car audio brand during the course of the last 3+ months and we’re pretty much positive we’ve found which ones are the best.

There were some surprising results…

On the table below is a comparison among the 3 best performing 4-channel amp series.

These are all 4 channel amplifiers, the best ones if you want to power a pair of speakers placed on the front doors and another pair on the back.

Good quality aftermarket speakers can blast really loud if they get the RMS they deserve, so definitely a smart investment!

Reasons to add an Amplifier

Here are a few of the main benefits of adding an amp:

  • Enhanced Sound Quality: By adding an amplifier you can enjoy a much cleaner, crispier sound at all volume levels. The external amplifier takes the clean pre-amp signal of your car stereo and amplifies it to the optimal level of RMS your speakers need, without adding further distortion to the signal. 
  • Power your Aftermarket Speakers: If you decide to upgrade your factory system with some high-quality speakers, you will be sad to discover they won’t sound good just with the signal your car stereo gives. You need to feed your brand new speakers with an amplifier so they get the RMS they were designed for if you want them to really sing. You can learn more about RMS at the end section of this article.
  • Amplifying a Subwoofer: Even a small 8″ subwoofer will need way more than what your factory stereo can give. Some powerful 4 channel amps will do good if you bridge 2 channels to power a small subwoofer but in general terms, subs need a lot of power. In most cases, you’ll need a separate monoblock amplifier to power them properly, or you could also go for a five channel amp in this case.

4 Channel Amplifier Reviews

Let’s be clear. There are hundreds of amplifiers on the market and that means, as always, that there’s a lot of garbage products out there that are just a waste of money. Brands like Boss or Pyle are incredibly cheap, both in price and quality.

After testing 50+ 4-channel amps, we’ve selected just four lines of amplifiers from the top three brands: JL, Rockford Fosgate and Hifonics.

There is a grand total of eight 4 channel amps, so every budget will find a great amplifier, and for any power needs you may have, you will find a great quality amplifier that gives just what you need. No filling, no “good” or “OK” amps. Just the best.

Comparison Chart

415+lrujVnL. SL500
41S4Uh74QdL. SL500
Rockford Fosgate P600X4 Punch 600 Watt 4 Channel Amplifier
41hUW21HbML. SL500
Hifonics BRX1116.1D Brutus Mono Super D-Class Subwoofer Amplifier, 1100-Watt
316mqcDtmLL. SL500
Kenwood KAC-M3004 Compact 600W 4-Channel Car/Marine/Powersports Digital Amplifier
Alpine MRV-F300 4-Channel Car Amplifier, 50 Watts RMS x 4

1. JL Audio XD400/4

415+lrujVnL. SL500

For us, there isn’t any better 4 channel amplifier. Of course, there’s Audison but from our experience, the difference is minimal and they’re so stupidly overpriced we won’t even talk about them. JL offers outstanding quality, great power output, lowest distortion levels and yet keeps the price on a reasonable term.


  • Amp Class: D Class
  • RMS: 75W RMS x 4 @ 4 ohms
    100W RMS x 4 @ 2 ohms150W RMS x 2 @ 8 ohms
  • Max Power Output: 400watts
  • Bridgeable: Yes
  • Features: State-variable, 12dB/octave Butterworth with continuously variable cutoff frequency selection from 50-500 Hz. Configurable as Low-Pass or High-Pass. Defeatable.

JL Audio XD400/4 Review

51sRvZJoh6L. SL500

Back side of the JL XD 400

The amplifier is extremely well built and the finish is impeccable. It has a lot of fantastic design details, such as the wires being secured with allen screws instead of flat or phillips, which allows you to tighten them down harder without stipping the screw heads as I have sadly (and embarrasingly) done a thousand times.

The controls of this amp are hidden underneath a cover which gives it a cleaner look, and the wire connections are all on the same side, making installation easy.

We’ve tested this amplifier with four of our favorite 6×9 speakers, the Rockford Fosgate R169X3 rated @ 65W RMS at were EXTREMELY satisfied with the consistent power output, the crispiness of sound and amazed at the fact that such a small amplifier could feed that power and not overheat the slightest bit. With the size, it is great to fit under any car’s seat and will work brilliantly.

The only downside we can find to this amplifier is the price, which sadly won’t fit every budget.


  • Extremely well built.
  • Really small, fits anywhere.
  • Great RMS output.
  • Excellent Heat Dissipation.


  • Prices higher than others

2. Rockford Fosgate P600X4 – 4-Channel Amplifier

41S4Uh74QdL. SL500

The Rockford Fosgate P600X4 – 4-Channel Amplifier offers impressively sharp, clear sound, garnering rave reviews. At the time of writing, this amplifier was retailing for between 300 and 400 dollars. That might seem pricey, but it’s a great deal for the quality and power it offers. It’s very versatile and compatible with most audio system configurations. It has also been praised for being easy to install. If you have the space for the Rockford Fosgate P600X4 – 4 Channel Amplifier, you won’t be disappointed with it. 


  • Power: peak power of 600 watts
  • Quality: Excellent 
  • Size: 2.38″ x 7.76″ x 13.28″
  • RMS Output:
    • 75 Watts x 4 @ 4-Ohm
    • 150 Watts x 4 @ 2-Ohm
    • 300 Watts x 2 @ 4-Ohm Bridged
  • Heat Dissipation: Convection

While on the more expensive side, the Rockford Fosgate P600X4 – 4-Channel Amplifier is fantastic and well worth the money. It offers amazing sound definition, a unique aluminum heat sink design for maximum cooling no matter how high your crank the power, and protection against short-circuiting. It’s on the large side weight and size-wise, so, unfortunately, it may be too large for some motorcycles and other smaller vehicles. It’s a Class AB amplifier, so it’s more energy-efficient than a Class A amplifier but may offer lower performance. We haven’t heard any complaints in that department, but several customers have reported that their amplifier died shortly after the one year warranty ran out even with just average usage. Luckily, that doesn’t appear to be a common problem. Still, it may not have the durability you’re used to seeing from Rockford Fosgate. 


  • Easy to install
  • Durable
  • Long lasting
  • Can Accept Both High and Low Audio Signals
  • High-Quality Components
  • Ideal For a 4-Way Full-Range System


3. Hifonics Brutus Series

41hUW21HbML. SL500

This amps are the most budget friendly from our selection. Hifonics has achieved an amazing quality/price ratio and are definitely our go-to choice when we need extra power and don’t have too much to spend (we talk about the biggest one, the BRX1616 which gives an amazing 400w per channel @ 2ohms… enough to power a nice block of four 8″ subs)

  • BRX316.4
  • BRX616.4
  • BRX1616.4



  • Amp Class: AB Class
  • RMS: 4x80W@ 2ohms
    4x40W @ 4ohms2x160W @ 4ohms
  • Max Power Output: 400watts
  • Bridgeable: Yes
  • Features:-Ultra-Fi MOSFETS Circuit maximizing power efficiency while improving sound quality

    -Preamp RCA outputs to daisy chain multiple amps

    3-way protection circuitry (thermal, overload, and speaker short protection)

    -Lighted connectors and blue wash of light from the underside of the heatsink



  • Amp Class: AB Class
  • RMS: 160W RMS x 4 @ 2 ohms
    80W RMS x 4 @ 4ohms
    320w RMS x2 @ 4ohms
  • Max Power Output: 600watts
  • Bridgeable: Yes
  • Features:Preamp RCA outputs to daisy chain multiple amps
    -3-way protection circuitry (thermal, overload, and speaker short protection)



  • Amp Class: AB Class
  • RMS: 400W RMS x 4 @ 2 ohms
    200W RMS x 4 @ 4ohms
    800w RMS x2 @ 4ohms
  • Max Power Output: 1600watts
  • Bridgeable: Yes
  • Features:Preamp RCA outputs to daisy chain multiple amps
    -3-way protection circuitry (thermal, overload, and speaker short protection)

Hifonics Brutus Series Review

As a first highlight of this amplifier, we find Ultira High-fi MOSFET inside it. It makes the amp power-efficient and reduces distortion to insignificant levels. Whilst amplifiers do not play a massive role on Sound Quality by themselves, they do if they produce additional noise, which isn’t at all the case.

The outside shell is made of aluminium alloy, which acts as a heat sink improving cooling. This is great, as the amplifier will last longer and you will enjoy great sound for good years.

It is retro-illuminated with LED light that adds some swag to the looks of the amp.

A LED pilot will flash green if everything works as it should and red if there is any kind of short circuit that could damage the internal components. To ensure nothing goes south in that case, the amplifier has a 3-way protection circuitry that includes thermal overload auto shut-off to protect both amp and speakers.

hifonics brutus light 4 channel

Light in detail

All in all, a great series of products. We’ve personally owned some Hifonics monoblocks for a couple of years that we use for subwoofer testing purposes and they do last. (And we don’t treat them exactly nice…)

These 4 channel amps are in no way 1ohm stable. Do not wire them @1 ohm because they fry within seconds. We’ve found thats the most common cause for user complaints on this amplifiers.

The most powerful version of this amplifiers will ask a lot of your car battery, so upgrading your battery for a better one or adding an auxiliary battery is a great choice.


  • Great RMS levels with 0 distortion.
  • Affordable
  • Awesome looks
  • Great heat dissipation on small models


  • Most powerful models get warm when pushed to the max. 

4. Kenwood KAC-M3004 – Compact 4 Channel Digital Amplifier

316mqcDtmLL. SL500

The Kenwood KAC-MC3004 – Compact 4 Channel Digital Amplifier is affordably priced, generally retailing for between 100 and 200 dollars. Its small size means it can be installed nearly anywhere, and its water-resistant coating makes it ideal for boats. You don’t have to worry about compromising quality for price or size with this amp!


  • Power: peak power of 600 watts
  • Quality: Good
  • Size: 6.69 x 3.15 x 5.91 inches
  • RMS Output:
    • 50 watts RMS x 4 channels at 4 ohms
    • 75 watts RMS x 4 at 2 ohms
    • 150 watts RMS x 2 channels at 4 ohms bridged
  • Heat Dissipation: Needs Air Circulation

If you’re looking for a compact but powerful amplifier, the Kenwood KAC-M3004 – Compact 4 Channel Digital Amplifier is for you. It’s durable enough to stand up to harsh environmental conditions and small enough that it fits most vehicles. Some people have had issues with it overheating, so make sure you have it somewhere it receives plenty of air circulation and out of direct sunlight.

Despite its size, this amp is capable of boosting sound output so you can easily and clearly hear your music, even over large amounts of noise on the road or water. It also offers signal sensing turn-on, so you don’t need a remote to activate the amplifier, it automatically comes on when you turn your stereo on. While Class D amplifiers are known for having weak high-frequency audio, we haven’t heard any complaints with the KAC-M3004 and it’s more energy-efficient than other amp classes. 


  • Easy to set up
  • Acceptable price


  • An S/N ratio of 76 dB is poor

5. Alpine MRV-F300

The Alpine MRV-F300 tends to retail for a little more than 200 dollars, making it middle of the road as far as amp prices go. The quality it provides is great for the price you pay, and it has been praised for a sleek and clean appearance. It offers the same amount of power as the previous model, but it’s 40 percent smaller and very light, so you’re no longer quite so constrained by the amount of installation space you have. The Alpine MRV-F300 has snap-on terminal covers to make installation easier, and this has proved to be a popular feature.


  • Power: peak power of 640 watts
  • Quality: Great
  • Size: 12.99 x 9.06 x 4.33 inches
  • RMS Output:
    • 75W RMS X 4 (2Ω , 14. 4V, ≤ 1% THD+N)
    • 50W RMS X 4 (4Ω , 14. 4V, ≤ 1% THD+N)
  • Heat Dissipation: Thermal Management Processor

The Alpine MRV-F300 stays cool under pressure, so you can play your music continuously and without interruptions, distortions, or pauses to let it cool down. It’s perfect for upgrading your existing system because it can connect to any head unit without needing an external converter. In addition to being smaller than its predecessors, the Alpine MRV-F300 is way more efficient. It’s Class D, providing clean power to your speakers.

Your bass will sound clear no matter what kind of power demands you’re placing on this little amp. Some people have complained that the MRV-F300 they ordered didn’t work when it arrived. This seems to be an unusual issue, but if you’re worried make sure you order from somewhere that offers free returns or gear4wheels1-20nts. 


  • Has the largest crossover range on our list at 50 to 400 Hz
  • Compact design
  • Stays cool under pressure


  • Expensive