What Are The Best 4 Channel Amps? – 2021 Edition
Once you start getting a bit more ambitious with your car audio, you’ll need a more flexible and capable car amplifier as the centerpiece.
If you’ve got four speakers in your set-up, a monoblock amp just won’t cut the ice. Whether you’ve got multiple door speakers or you want to bridge the amp to supply a pair of full-rangers and a sub in back, you’ll get incredible versatility from a 4 channel unit.
The market is saturated with poor quality amps so navigating this minefield can be tricky.
Today, we’ll review 10 of the best 4 channel amp options so you can safely invest in a car amplifier tailored to your needs and budget.
- 10 Best 4 Channel Amps of 2021
- 1. JL Audio 4 Channel Amp (XD400/4)
- 2. Rockford Fosgate 4-Channel Amp (R250X4)
- 3. Hifonics Brutus 4-Channel Amp (BRX1616.4)
- 4. Alpine 4-Channel Amp (PDX-F6)
- 5. Boss Audio Phantom 4-Channel Amp (PH4.600)
- 6. Infinity Kappa 4-Channel Amp (K4)
- 7. Rockford Fosgate Punch 4-Channel Amp (PBR300X4)
- 8. Kenwood Compact 4-Channel Digital Amp (KAC-M3004)
- 9. Alpine MRV F-300
- 10. Kicker CXA 300.4
- Frequently Asked Questions (FAQ)
- What’s the difference between two-channel and four-channel amps?
- Why should I choose a four-channel amp?
- How much power do I need?
- What kind of installation options do I have?
- How do I choose a good amp?
- Do I need a class D amp?
- What are the differences between AB amps and D amps?
- How many speakers can I run with a four-channel amp?
- My head unit has two channels. Can I connect a four-channel amp?
- Can I bridge my four-channel amp?
- In Conclusion
10 Best 4 Channel Amps of 2021
1. JL Audio 4 Channel Amp (XD400/4)
JL is a serious player in the car stereo space and the XD400/4 is consistently among the top 4 channel amps on any shortlist. With rugged build quality, outstanding peak power and minimal distortion, the only surprising part is that it doesn’t cost more. For an affordable alternative to the wincingly expensive Audison, there’s no substitute for JL amp.
- First-class build quality
- Consistent power output
- Sound is crisp and clear
- Not the cheapest 4-channel amp
JL Audio has kept all the controls covered up on the XD400/4 so, while this amp packs some serious features, the aesthetics remain lean and mean.
Watts RMS rating is 75 watts per channel at 4 ohms, 100 watt at 2 ohms and 150 watts at 8 ohms. Peak power output is extremely level and offset with a real clarity. Despite this grunt, the amp won’t overheat even under heavy punishment.
The JL is nice and compact too so you can slot it more or less anywhere even in a smaller vehicle. The covered controls are ideal if your tastes err to the minimalist.
For a big sound in an enticingly small package, you should check out this awesome 4-channel amp at your earliest convenience.
It packs quite a punch for a small speaker, delivering a full range of sound with clear highs and lows. You can directly control it right from your driver’s seat while offering full bandwidth Class D operation. It’s efficient and provides low distortion, improving sound, and giving you a cleanly powered sound. Overall, it’s a heavy hitter in a small package.
2. Rockford Fosgate 4-Channel Amp (R250X4)
Rockford Fosgate strongarms onto the scene in any roundup of the best car stereo equipment. You get brand heritage and build quality rolled out in a package that’s surprisingly affordable. The R series is all budget-friendly and we opted for the lower-end R250X4 which offers exceptional value without any dip in performance.
- Wide range of settings
- Cheaper than expected
- Slimline unit
- Tends to run hot
- Features can be overwhelming for beginners
With amps at this price point, you can easily end up with a piece of junk that’s fried not long after installation. Although this A/B class 4-channel suffers from overheating to some extent – there’s no cooling fan – this should by no means be considered a deal-breaker.
Watts RMS power is 40 watts per channel at 4 ohms, 60 watts at 2 ohms and 125 watts x 2 at 4 ohms when bridged. This is restrained for a 4-channel but still more than fit for purpose.
These amps come with a testing certificate. A rarity in the car stereo world, the tested wattage actually outflanks the claims figures rather than falling woefully short.
You’ll enjoy a wide spread of settings with the Rockford Fosgate so it’s well worth taking your time to tweak things to match your tastes. Heating issues set aside, this is one of the best 4-channel amps on the market.
Rockford’s amp allows you to hook up rear sound easily through RCA builtin throughputs. Along with a voltage sensor that bypasses the need for manual operation, it offers enough customization and choice to provide excellent installation and sound experience from an affordable speaker. If you need a reliable player in your sound system, this could be a straightforward option.
3. Hifonics Brutus 4-Channel Amp (BRX1616.4)
Hifonics offer budget amps with mid-tier performance which is an appealing combo. Available in 3 sizes, we went for the largest 4-channel, the BRX1616.4 and the peak power to price is pretty much unbeatable. If you want to serve multiple speakers or a block of small subs, this amp is the ideal solution.
- Excellent Watts RMS power
- Superb heat dissipation
- Great aesthetics
- May warm up when maxed out
Although the sound quality in your system doesn’t hinge solely on the amp, if this unit kicks out additional noise it will be a menace. The Brutus keeps background distortion to an absolute minimum.
Thanks to the aluminum alloy casing, cooling is optimized. Unless you run this amp super-hard, you should get no trouble from overheating. Class AB amps always win out on the heat dissipation front.
RMS power is 400 watts per channel at 2 ohms, 200 watts per channel at 4 ohms and 800 watts bridged. Do not wire them at 1 ohm or they’ll burn out. As long as you consider upgrading your battery, this capable 4-channel BRX amp will reward you with plenty of powerful service.
Hifonics offers unmatched power with good, reliable sound. There’s low distortion and reduced background noise, but the potential heat could be a concern if you wire your speaker any lower than two ohms. Otherwise, your cooling is a straightforward matter. Power is prioritized, and the speaker is a workhorse in a smaller package.
4. Alpine 4-Channel Amp (PDX-F6)
A pricier 4-channel amp from Alpine is up next, the hard-hitting PDX-F6. This class D car amplifier packs plenty of power in a compact chassis and runs cooler than you’d expect for this class. If you want to stack them, the heat sinks will cool the whole stack. This amp is ideal for any vehicle with limited space.
- Crisp, clear sound
- Superb power handling
- Switchable to 2-channel
- Pretty expensive
Alpine specializes in top-notch car stereo that, while not cheap, still represents excellent value considering what you get for your money.
If you have a truck or sports car, space inside is at a premium. For anyone driving a compact vehicle but not prepared to stint on their audio, this slimline, stackable amp is tailor-made.
RMS rating is 150 watts per channel at 4 ohms or 2 ohms. In bridged mode you’ll get an impressive 300 watts. As well as sheer power, the sound is extremely clean, something that shines through in almost all user reviews.
Installation is straightforward even if you’re stacking multiple amps and the overall build quality is first rate. For a rock-solid class D amp in a very small chassis, the Alpine PDX-F6 is right up there with the very best.
5. Boss Audio Phantom 4-Channel Amp (PH4.600)
Boss Audio occupy a steady spot in the car stereo market delivering decent gear at a reasonable price point. This 4-channel class AB is no exception. For efficiency, minimal distortion and a deep and loud sound, the PH4.600 class AB punches above its weight. It’s hardly a budget amp but it will still leave you plenty of wiggle room for speakers or a sub.
- Very versatile
- Thumping bass
- Outstanding power
- Some reported glitches with thermal protection
Boss Audio has really leveled up with the Phantom. Power handling is outstanding with 240 watts per channel at 4 ohms. As well as outright volume, you’ll also enjoy a thudding bass with the ability to drive some serious speakers.
Often, if you push the volume hard on an amp, sound quality takes a significant dip. That’s not the case with the Phantom. Even when the dial is jacked right up, there’s a warm and depth to the bass that would be surprising if you didn’t know Boss Audio’s heritage.
Build quality is truly impressive. You’ll get gold-plated connections, superb cooling and efficiency across the board.
You can hook this amp up in multiple configurations so whether you want to drive several speakers, a subwoofer or a combination, Boss has you covered. Overall, this is one of the strongest 4-channel amps on the mainstream market.
6. Infinity Kappa 4-Channel Amp (K4)
Increasingly, consumers are looking for enhanced connectivity with amps. The Infinity Kappa 4-channel is Bluetooth-enabled allowing you to savor a wider selection of music without needing a huge stack of CDs. Coming in a stylish chassis and possessing ample power for a decent pair of speakers, the Infinity Kappa is a smart choice.
- Bluetooth connectivity
- Nimble power handling
- Striking aesthetics
- Controller less than ideal
- No Bluetooth volume adjustment
If you place convenience uppermost, you’ll love the fact you can stream music from any Bluetooth-enabled device to this nifty little 4-channel car amp. The best part? Sound quality lost during compression is neatly restored with Clari-Fi technology to further enhance your listening pleasure.
You can drive a pair of hefty speakers with 100 watts RMS per channel. Bridged to a couple of subs, you can get 240 watts RMS per channel so you won’t lose out on firepower in the quest for convenience.
The wired remote control allows you to easily navigate any Bluetooth streaming and you can also take advantage of hands-free calling making this a truly multi-purpose 4-channel car amp.
Not only does this amp step up to the plate on the sound quality front, it looks lean and stealthy into the bargain. Priced competitively, the Infinity Kappa will not disappoint.
7. Rockford Fosgate Punch 4-Channel Amp (PBR300X4)
As we near the end of our 4-channel amp reviews, another compact model from the mighty Rockford Fosgate. Whether you’ve got a truck, an ATV or even a motorbike, this dinky little unit packs an extreme Punch just like its name suggests. Coming in at a very keen price point and with enough power for the majority of speakers, this is a 4-channel amp with a difference.
- Incredibly small footprint
- Exceptional heat dissipation
- Superb value
- Not possible to bridge
- Only stable at 4 ohms
Not everyone is looking for a slab of an amp and for many out there with smaller vehicles, getting a great 4-channel amplifier that fits inside is tough. Rockford Fosgate has addressed this issue head-on and the PBR300X4 is a wolf in sheep’s clothing.
If you think an amp this compact will stiff you on the power front, you’d be sorely mistaken. Watts RMS is 75 watts per channel at 4 ohms maxing out at 300 watts. While 75 watts might not be enough sound to fill a stadium, it’s more than sufficient for a smaller vehicle.
Even if you blast this amp, heat dissipation thanks to the aluminum heat sink keeps the temperature down even as the volume rises.
The only real complaints are the fact the Punch is only stable at 4 ohms and it’s not bridgeable. Considering the power to size ratio and the price tag, not to mention the brand you’re buying into, you can’t judge this 4-channel amp too harshly for those small flaws.
8. Kenwood Compact 4-Channel Digital Amp (KAC-M3004)
Kenwood has a hard-won reputation for delivering quality sound at a sensible price point across the full range of car audio. This 4-channel digital amp sticks firmly with that tradition. Much like the Rockford Fosgate, this amp is expressly designed to slot into tight spots without eating up too much space. If you’ve got a compact size vehicle but you still want substantial sound, the KAC-M3004 is a great audio solution.
- Works well in smaller vehicles
- Ideal for boats thanks to coated circuitry
- Easy installation
- Prone to overheating like all class D amps
Smaller amps that don’t stint on power can be tough to find. The Kenwood KAC-M3004 is a scaled-down 4-channel that comes in a sleek chassis with more than enough performance for most reasonable requirements.
Through 4 channels, you’ll get 50 watts RMS per channel. Bridging delivers 150 watts to each of a pair of subwoofers.
Although this is a car audio site, many car fans are also partial to a quick blast in a speedboat. If you want to take this amp out on the water, conformal coating on the circuit board allows you to do that safely.
Alongside winning looks, thumping performance and a slimline body, the Kenwood is built to last and it’s an absolute cakewalk when it comes to installation. It’s also priced low so this is a wonderful 4-channel amp even if you’re operating on a tighter budget.
9. Alpine MRV F-300
The biggest plus for this speaker is the ease of installation. It’s configured for a surface mount but doesn’t require external converters. The terminal covers use snap-on covers, and it’s roughly 40 percent smaller than the previous speaker model.
- The anti-shutdown feature keeps things cooler
- Easy to install with no external converters
- Smaller than previous models with less power
- Directs more low sounds to the subwoofer
- No RCA outputs
If you’re limited in your placement, Alpine makes an excellent series of speakers and amps designed to accommodate rear speakers or door speakers. The MRV F-300 is an excellent option, and the compact profile helps reduce heat and power consumption. Overall, it’s a cleanly performing amp with lots of features.
It performs well with good sound. It has an excellent THD, which can run as low as .03 percent, but with the standard four-channel configuration, it still features one percent (an industry standard). The subwoofer needs no more than 100 watts of power, but it will direct more of your lower sounds to your subwoofer.
You do have more limitations in configurations, especially with a subwoofer, but the power output is excellent for a rear sound or door speaker. Its casing gives you a much easier time when placing it for a door location. It has an anti-shutdown feature that helps it run cool, and it doesn’t sacrifice much power in operation.
10. Kicker CXA 300.4
The performance is distinctly better than some of the cheapest amps out there, but it gives you some wiggle room in your budget requirements.
- Affordable price point for beginners
- Offers good performance for experimenting with sound installation
- S/N ratio is 95db
- Larger housing is bulky to try to install
If you need a budget style four channel amp, Kicker is a good place for beginners to get started. It may not be a legacy amp, but it does deliver reliable performance at a much more affordable price. You can play around with it without worrying about losing your investment if you make a mistake wiring.
It’s one of the least expensive amps on the list without sacrificing a clean power drive and an S/N ratio of 95db. Not too shabby for a budget style amp. It is a bit larger than many of the amps on the list however, so you’ll sacrifice some installation flexibility. It makes up for its lack of a slim profile by delivering a solid, mid-range performance for a low-range budget.
It does have an efficient cooling system, although there’s no built in fuse. It functions at 4 ohms or 2 ohms – a decent performance for an amp in this price range. However, the wattage is fairly low, so be sure you know how to find compatible pieces for your complete sound package.
Overall, this one is good for experimentation or for getting a quick sound system up when you don’t need much power.
Frequently Asked Questions (FAQ)
What’s the difference between two-channel and four-channel amps?
A four-channel amp can be wired as a two-channel, which may be why some people get confused. A four-channel amp has the capability of two two-channel amps but in a smaller housing that eases installation. You can bridge it to use two or three channels, providing greater flexibility.
Why should I choose a four-channel amp?
Four-channel amps are highly versatile and provide multiple channels to power multiple speakers plus a subwoofer. You can use two of the channels for your speaker hookups and then bridge the final two to drive the sub. If you plan to expand your speaker system in the future, it’s best to go bigger.
How much power do I need?
More than you might think. You never want to skimp on power and run the risk of not getting the sound you really wish to — double-check when you’re picking out your speakers that your amp has enough power to drive sound. Otherwise, you’ll be really disappointed in what you get the first time you turn on your system.
Find the watts RMS (root mean square) of your speakers and look specifically for an amp that can provide at least 75 percent of that number. You don’t want more than 150 percent, however, or it may overheat.
What kind of installation options do I have?
Wiring a car amplifier isn’t super complicated, but there are a few things to consider before you get at it. When you’re shopping for your unit, consider where you’ll be putting it in the car and how you’ll wire it to help narrow down the right one.
Since most cars don’t come with preamps, you’ll have to find new space for them. Take some measurements to make your shopping easy. Popular locations include under seats, against the passenger side firewall, or even in the trunk. Consider and measure all these options before you head out shopping.
How do I choose a good amp?
The best amp for your vehicle matches the schematics and installation method while providing enough power. However, if you also need to consider a here are a few things you can look for when you’re shopping for the right amp.
Excellent signal to noise ratio – SNR is usually designated in decibels. A good amp should have at least SNR 90db or above to improve sound quality. Specs can be misleading, however, so you need to check that it performs at a variety of power outputs.
Crossover options – Crossover, whether high pass or low pass gives you more power with less distortion. Four-channel amps allow a fuller range of sound to happen with very little distortion on the low end. For smaller speakers, it’s impossible to get that kind of sound. You’ll need a model with a built-in high pass and low pass crossovers.
Design – Poorly designed amps pass over quite a few details that can make it easier to install and more straightforward to maintain. Well-designed amps have thicker printed circuit boards and higher quality components. They also include surface-mounted components for easier installation. Proprietary circuits are also an excellent choice.
Watts RMS Ratings – The Consumer Electronics Association provides compliance standards to help combat confusing or misleading ratings from a variety of companies. Shop for models that provide CEA ratings.
Do I need a class D amp?
Class D car amplifier are newer technology designed to smooth out some of the sound issues of older Class AB amps. Class D works with a different type of power supply that modulates the audio signal and reconstructs the signal to provide a smooth sound.
What are the differences between AB amps and D amps?
In addition to the different power supply, AB amps are a bit bulkier than Class D, so you’ll have to find more room in your installation. They consume more power and tend to run hot. Many of them are drawing a lot more power than what’s rated on the unit. Many of them aren’t more than 65% efficient, meaning you’ll end up with a lot of heat on the unit.
How many speakers can I run with a four-channel amp?
A 4 channel can be configured quite a few different ways. It depends a lot on how you choose to wire the speakers, but you have the potential to wire up to eight speakers from your amp.
My head unit has two channels. Can I connect a four-channel amp?
If you have two RCA Y adaptor cables, you can connect the two channel head unit. Manufacturers make it much easier to connect the two, and once you’ve got them connected, you can adjust the gain to balance the sound of the rear speakers.
Can I bridge my four-channel amp?
There are lots of advantages to bridging your amp. It improves versatility and adds the ability to power speakers and a sub. Bridging can change the impedance, however, and potentially damage your amp. However, if you can talk to someone with experience, you can easily make that happen.
We trust you’ve found some suitable 4-channel amps on this list so you can assemble your personalized shortlist and spend your hard-earned money wisely.
If you think about exactly what you want from your car amplifier and take the time to do plenty of research, you’ll have your speakers and sub fired up and rocking with the best power plant possible.
Come back soon and don’t forget to check out our handy guide to buying the best car amplifier for your ride.