Best 4 Channel Amplifier for Better Sound Quality

An amplifier is an essential component in building a great aftermarket car audio system. It’s a key product for anyone who cares about great sound quality, and not just seasoned audiophiles.

The reason being: car head units are equipped with built-in amps, but many of these aren’t much to write home about. So, if you want your speakers to really sing, amplifiers are definitely part of the picture.

The first thing to do is to read our unrivaled car amplifier buying guide in which we explained in details all the relevant specifications and guidelines of how to choose the best amplifier for your vehicle.

External car amplifiers are categorized by the number of channels. In other words, they are are categorized by the number of speakers they can power simultaneously. There are mono channel amps and multi-channel amps – with 2, 4, 5 and 6-channels.

For the purpose of this article, we’ll be reviewing a few of the best 4 channel amplifiers on the market.

So, without any further ado, onto the reviews!

Rockford Fosgate R400-4D Specifications

  • Number of Channels : 4
  • Bridgeable : Yes
  • Class : D
  • RMS Power 
    • @ 4-Ohm : 75 Watts x 4
    • @ 2-Ohm :  100 Watts x 4
    • @ 4-Ohm Bridged : 200 Watts x 2
  • Max Power : 400 Watts
  • Frequency response : 20 – 20,000 Hz
  • Features
    • Variable high- and low-pass filters (50-250 Hz, 12 dB/octave)
    • Variable Punch EQ bass/treble boost (0-18 dB at 45 Hz and 12,000 Hz)
    • Preamp inputs and outputs
  • Warranty: 1 year

When it comes to external car amplifiers, Rockford Fosgate is probably one of the most legendary. They offer a wide range of reasonably priced car amplifiers.

Rockford Fosgate amplifiers come in three categories labeled Prime, Punch, and Power. RF’s “Prime” series amps are considered to be the RF’s most value-priced models while “Power” subs are the high-end line. Punch series amplifiers are more of a middle-of-the-road line of amps. They represent the perfect mix of power and price.

The R400-4D is one of the top rated 4 channel amplifier on the market. It uses a class D topology, which makes the amplifier energy efficient with very low operating temperatures.

The Rockford Fosgate R400-4D is one of the best car amplifier under $200. It can put out up to 75 watts RMS to each of your front and rear speakers, which is more than enough to push them to their full potential. This 4 channel amplifier is bridgeable. In other terms, you can use two of its channels to drive your front speakers while using the other two channels bridged to run a subwoofer with up to 200 watts RMS. And, of course you can bridge the whole amp to 2-channel mode to drive a couple of subs.

This amplifier comes with various features including high- and low-pass filters, along with Rockford Fosgate’s famous Punch EQ bass/treble boost, so you can tune your stereo system to get a well-balanced sound output.

PROS

  • Excellent sound quality for its price
  • Lightweight and durable construction
  • High power efficiency
  •  

CONS

  • Capable of supporting only 4-Ohms in bridged mode
  •  

Rockford Fosgate P600X4 Specifications

  • Class : A/B
  • Number of Channels : 4
  • RMS Power
    • @ 4-Ohm : 75 Watts x 4
    • @ 2-Ohm : 150 Watts x 4
    • @ 4-Ohm Bridged :300 Watts x 2
  • Total Power : 600 Watts
  • Bridgeable : Yes
  • Frequency response : 20 – 20,000 Hz
  • Features
    • Variable high- and low-pass filter filter (50-250 Hz, 12 dB/octave)
    • Variable PEQ2 bass/treble boost (0-18 dB at 45 Hz and 0-14 dB at 12.5K Hz)
    • Preamp inputs and outputs
    • Speaker-level inputs

The P600X4 is another great 4 channel amplifier by Rockford Fosgate. It’s going to be the most expensive pick of the lot by far. It is the best performing amplifier in Rockford Fosgate Punch series. It’s very well-engineered and would be a great investment for anyone who’s looking for a solid car amplifier with an impressive power output.

At 4 ohm, the P600X4 can put out 75 watts RMS to each of your front and rear speakers, which is plenty of power to make your aftermarket speakers sing.  You can also switch this amp into 2-channel mode – also known as amp bridging – to drive a couple of subs with up to 300 watts RMS each. You can use the amp’s high-pass filter to filter out and prevent the amp from sending low frequencies to your speakers so they’ll play more efficiently. Similarly, you can use its low-pass filter to avoid sending high frequencies to your sub(s). The Punch EQ2 includes bass and treble boosts, in case you want to add some boom and sizzle back into the mix.

To easily match this amp to your receiver’s output, Rockford Fosgate went a step ahead and fitted the P600X4 with their C.L.E.A.N. technology which stands for Calibrated Level Eliminates Audible Noise. C.L.E.A.N. is a technique to ensures your music will sound as clean and powerful as possible. It works as follows :

  • Play the setup tone on the included test CD
  • Adjust the receiver volume until a red clip light on the amp goes out
  • Then turn the amp gain up until a blue light comes on
  • Once the Blue light comes on, your amplifier is matched to your headunit’s output.

If I had to pick some criticisms for this amplifier it would be the price. This amplifier is a bit highly priced than most. However, something this good is naturally expensive. So, if you don’t mind shelling out a few extra bucks, the Rockford Fosgate P600X4 could make day and difference in terms of sound quality, and of course, assuming you’ve got some great sound car speakers.

PROS

  • Capable of producing clean, bass-heavy sound
  • Comes with a range of customizable options
  • High S/N ratio at 105/85 CEA dB
  •  

CONS

  • A bit more expensive than the other amps on this list
  • A bit heavy at 12.8 pounds
  •  

Kenwood KAC-8406 Specifications 

  • Class : A/B
  • Number of Channels : 4
  • RMS Power
    • @ 4-Ohm : 70 Watts x 4
    • @ 2-Ohm : 100 Watts x 4
    • @ 4-Ohm Bridged : 200 Watts x 2
  • Max Power : 900 Watts
  • Bridgeable : Yes
  • Frequency response : 5 – 50,000 Hz
  • Features
    • Variable high- and low-pass filters (50-200 Hz, 12 dB per octave)
    • Switchable bass boost (0, 18 dB at 40 Hz)
    • Preamp inputs
    • Speaker-level inputs with signal sensing turn-on

Kenwood is one of the most recognized brands in the car audio industry. They offer a well-rounded collection of various car audio components including headunits, amplifiers, subs, and speakers.

The KAC-8406 is one of the best 4 channel amp under $200 that Kenwood has to offer. It’s designed to deliver 70 watts RMS per channel to your speakers. Or you can Switch it over to bridge mode, and you can get great performance from a set of powerful components or a couple of subs with up to 200 watts RMS per channel.

The Kenwood KAC-8406 uses class AB design and MOSFET power supply. It comes with high- and low-pass filters, preamp inputs and speaker-level inputs with signal sensing turn-on.

PROS

  • Offers great power and sound quality
  • Doesn’t heat up compared to other amps
  • A great option for those on a budget
  •  

CONS

  • Doesn’t come with a line out
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JL Audio JX400 Specifications

  • Class : D
  • Number of Channels : 4
  • RMS Power 
    • @ 4-Ohm : 70 Watts x 4
    • @ 2-Ohm : 100 Watts x 4
    • @ 4-Ohm Bridged : 200 Watts x 2
  • Max Power : 900 Watts
  • Bridgeable : Yes
  • Frequency response : 20-20K Hz
  • Features
    • Variable high- and low-pass filters (50-200 Hz, 12 dB/octave)
    • Preamp inputs and outputs
    • Speaker-level inputs

JL Audio is a brand we haven’t come across very much at all. However, they’re making a name for themselves in the car audio industry. Their JX400 in one of the best compact 4 channel amplifier on the market. Its tiny size makes a great option for people with very limited space inside their vehicle as well as for those who don’t want to sacrifice their cargo space.

Despite its small size, the JL Audio JX400 is quite powerful. It can put out 70 watts RMS to each of its four channels. In bridge mode, this versatile amplifier can power a pair of speakers or subs with 200 watts RMS each, and fill your ride with well-balanced sound.

The JL Audio JX400 is a very well-engineered amplifier. Its controls are nicely labeled and well spaced out. It comes equipped with variable high- and low-pass filters, speaker-level inputs, along with pre-amp inputs and outputs, so its compatible with virtually any car stereo.

As for cons, it’s really difficult to think of any. If anything, I’d say that the JX400 is a bit pricey. So if you don’t mind shelling out some extra dollars, the JL Audio JX400 would a great, quality compact 4 channel amplifier to buy.

PROS

  • Allows daisy-chaining to other amps
  • Small and lightweight profile
  • Compatible with any stereo on your car
  • Excellent sound quality with little to no distortion
  •  

CONS

  • Can produce a bit of feedback noise
  • A bit pricey compared to other amps
  •  

Kenwood KAC-M3004 Specifications

  • Class: D
  • RMS Power
    • 4-Ohm: 50 Watts x 4
    • 2-Ohm: 75 Watts x 4
  • Max Power: 600 Watts
  • Bridgeable: Yes
  • Features
    • Built-in high and low-pass filters (50 to 200Hz)
    • Low distortion at all voice levels

When it comes to affordable 4 channel amps, the KAC-M3004 from Kenwood is no doubt the cheapest amplifier yet in our list. Thanks to Kenwood’s reputation in the audio equipment industry, we see no reason why you shouldn’t try investing in this product.

One of its key features is that it’s very easy to use to install. It features a peak 600W power output which is more than enough for most car owners. Apart from that, you can even use it with a three to four-speaker setup.

PROS

  • Excellent sound quality
  • Relatively affordable price
  • Good-looking aluminum finish

CONS

  • Not ideal for those who want a warmer sound

Rockford Fosgate R300X4 Specifications

  • Class: A/B
  • RMS Power
    • 4-Ohm: 50 Watts x 4
    • 2-Ohm: 75 Watts x 4
    • 4-Ohm Bridged: 150 Watts x 2
  • Max Power: 600 Watts
  • Bridgeable: Yes
  • Features
    • Speaker-level inputs
    • Built-in temperature and current sensors
    • Heavy cast-aluminum chassis

Yet another Rockford Fosgate product, the R300X4 is a class A/B amplifier which produces a far efficient sound quality and less distortion than most class A and B amps in the market. It comes with tons of power as well as a crisp tone at all sound levels.

Technically speaking, the R300X4 is an all-round amp capable of delivering between 50 and 150 watts per channel. It includes a number of amazing features including temperature sensors, aluminum chassis, and speaker-level inputs.

Overall, it’s a really good audio system amp for any standard setup.

PROS

  • Comes in 2 and 4-channel modes
  • Excellent protection features
  • Cast aluminum heatsink

CONS

  • Can heat up if mounted in an area without good airflow

MTX Audio THUNDER75.4 Specifications

  • Class: A/B
  • RMS Power
    • 4-Ohm: 75 Watts x 4
    • 2-Ohm: 100 Watts x 4
    • 4-Ohm Bridge: 200 Watts x 2
  • Max Power: 400 Watts
  • Bridgeable: Yes
  • Features
    • Variable low and high-pass filter (10 to 200Hz, 12dB/octave)
    • Low distortion at all voice levels

The Thunder series from MTX has been in the market for more than 20 years already. This alone is enough to speak for the quality of its products. The Thunder75.4 amplifier is currently the smallest Thunder amp they have in production.

It comes with a surface mount design for enhanced vibration resistance even on uneven surfaces. Just like most 4-channel amps, it also has variable crossovers. Additionally, its compact build quality won’t compromise your audio quality, not to mention it’s very easy to install and use.

Lastly, while it won’t provide you with the highest sound quality, it sure is a great choice as far as affordability is concerned.

PROS

  • Compact design for an amp of its class
  • Surface mount design
  • Excellent THD rating

CONS

  • Produces a lot more heat than most class A/B amps

Alpine MRV-F300 Specifications

  • Class: D
  • RMS Power
    • 4-Ohm: 75 Watts x 4
    • 2-Ohm: 50 Watts x 4
    • 4-Ohm Bridged: 150 Watts x 2
  • Max Power: 640 Watts
  • Bridgeable: Yes
  • Features
    • Superfast switching technology for excellent power efficiency
    • Variable high and low-pass filter

Despite its pretty small and compact size, the Alpine MRV-F300 is packed with decent power, easy installation, and excellent sound amplification. It’s a class D amplifier with a smart design and weighs only 4 pounds, making it one of the lightest amplifiers in the market.

Aside from that, it has an excellent build quality due to its stainless steel housing. If you have a main amp and planning to install a second one, then this could be a really good option.

PROS

  • Compact and lightweight design
  • Flexible built-in crossovers
  • Easy-to-use switches and controls
  •  

CONS

  • No RCA outputs
  • Pretty poor ratio S/N ratio at 98/81 CEA dB
  •  

Pioneer GMD8604 GM-D8604 Specifications

  • Class: D
  • RMS Power
    • 4-Ohm: 100 Watts x 4
    • 2-Ohm: 150 Watts x 4
    • 1-Ohm: 125 Watts x 4
    • 4-Ohm Bridged: 300 Watts x 2
    • 2-Ohm Bridged: 250 Watts x 2
  • Max Power: 1,200 Watts
  • Bridgeable: Yes
  • Features
    • Variable high and low-pass filter (40-500 Hz, 12dB/octave)
    • Small, lightweight, and compact amp

Pioneer is another excellent brand that offers affordable yet quality stereo components. The Pioneer GM-D8604 amplifier provides you with decent sound at a relatively affordable price. Additionally, its compact design allows you to fit it into your car without any problem.

If you’re looking for an amplifier which is a good balance between performance and affordability, then you certainly won’t be disappointed with the GM-D8604. In our experience, it was more than enough to provide us with a crisp and excellent audio quality in our car with a bass-heavy sound.

PROS

  • Highly efficient class D topology
  • Easy to install in small and tight spaces
  • Excellent quality at an affordable price

CONS

  • Has a tendency to heat up during operation