Best Mono Block Amplifier Review
The Kenwood KAC-9106D 2000W Monoblock Class D Car Audio Power Amplifier

Mono Block Amplifier Reviews And Guides

Monoblock amplifiers are one-channel units that output a ton of power. Hence, they’re designed to be paired with subwoofers, which require much more power than regular speakers.

This year, I had the pleasure of trying out 15 of the best mono block amplifiers currently in the market. After a couple of days with each (connected to my own car audio setup), I managed to shortlist them down to a top five, each of which I’ve reviewed below:

Best Mono Block Amplifiers

A Simple Buying Guide for Amplifiers

Before we get to the reviews, let’s talk a bit about how you might go about finding the best amplifier for yourself – one that not only suits your audio needs but is also compatible with current car setup. The key is to familiarize yourself with a few important technical specifications such as the class, power output, impedance, sensitivity…etc. This is the kind of stuff that our eyes usually skim over when we’re reading product descriptions but in this case, they’re important to know about. You’ll see why!

Amplifier Class

Amplifiers belong to different classes with the most popular ones being: A, B, A/B and D. The biggest difference between each class is efficiency, which in this context is a measure of how much Alternating Current (AC) can be supplied by an amplifier while consuming the least amount of Direct Current (DC) possible. Here’s a brief summary of how efficiency varies between the classes:

Class A

Class A circuits conduct electricity 100% of the time which unfortunately leads to a lot of wastage. This is because only a small amount of the current produced will be utilized by speakers and any other device connected to the amplifier. The rest will be converted to heat. Hence, Class A amplifiers can overheat with prolonged use.

The biggest advantage of Class A amplifiers is that they produce the purest signal.

Class B

Compared to Class A, Class B circuits only conduct electricity around 50% of the time. This brings up the efficiency level to around 70%. The biggest drawback of Class B circuits is that they tend to produce slightly distorted signals.

Class A/B

Class A/B circuits combine elements from both Class A and Class B, offering the best of both worlds. The Class B chain contains biasing diodes which eliminate any distortion from the signal path. Hence, you get both the signal purity of Class A and the power efficiency of Class B.

Class D

Class D amplifiers are the most efficient (90% to 95%) which has a lot to do with the fact that when they’re off, they’re truly off. This means that the output transistors do not retain any electricity and hence there isn’t any excess that can be converted to heat.

Power Output

The entire purpose of amplifiers is to make things loud and they achieve this by directing more power to our speakers and head units. The more power it outputs, the louder you’re able to get. However, there’s a limit to how much power your speakers candle. Cross this limit and they’ll overheat and blow out.

Fortunately, your speakers’ power-handling specifications, the RMS and Peak Power, will tell you what you need to know. The RMS indicates how much power (in watts) is safe to supply to the speaker on a regular basis while the Peak Power sets an absolute maximum. I found the RMS to be a more useful metric since it’s more relevant to day-to-day usage of speakers.

Amplifiers have RMS and Peak Power ratings as well but they’re related to power output instead of handling. Hence, when you’re buying an amp, make sure that you consider both its and your speaker’s specifications. The latter’s power-handling should be greater than or at least equal to the former’s power output.

Speaker Sensitivity

Speaker sensitivity indicates how loud a speaker will get (in decibels) when supplied with just one watt of power. For example, if your speaker’s sensitivity is 85 dB then it’ll get moderately loud with one watt driving it. With each additional watt you supply, you add 3 dB to the volume.

Speaker sensitivity is useful when you’re trying to determine how much power you need. The more sensitive the speaker the lesser the power you’ll need to reach a certain volume.

Frequency Response

Frequency response gives you the range of frequencies that an amplifier can handle. If the response is listed as 20 Hz to 20 kHz, this means that it’ll be able to handle all the frequencies that exist within the human audible range. Pretty much all monoblock amplifiers have a response spanning between 20 Hz to 250 Hz, which means that they can only handle bass frequencies. As a result, they can only work with subwoofers or woofers.


Impedance measures the internal resistance (in ohms) found in the amplifier’s circuit. The greater the impedance, the lower the amount of current that an amplifier can supply at any one time. Hence it’ll have to work harder. While low impedance generally puts less stress on the amplifier, it can potentially harm your speakers. If the impedance is too low, the amplifier may supply more power than what the speaker can handle, causing permanent damage.

By default, most amplifiers are set to an impedance of 4 ohms and often you get the option to switch to a lower setting. Before you do, make sure that your speaker or subwoofer can handle the larger influx of power.

The Number Of Channels

The number of channels you’ll need in an amplifier depends on the number of speakers and/or subwoofers you’ve got in your setup. Amplifiers that have five or more channels usually have high-powered dedicated subwoofer outputs. With others, you might be able to ‘bridge’ several channels into one in order to pair with a sub.

With monoblock amplifiers, you only get one high-powered channel. Hence they’re most suitable for when you need a separate amp for powering a sub.

The Top Five Picks

Now that you’ve received a crash course on what to look for when purchasing an amplifier, let’s take a look at my top five amplifiers for this year, starting with the…

Skar Audio Rp-1200.1d

Skar Audio RP-1200.1D Monoblock Class D MOSFET Amplifier with Remote Subwoofer Level Control, 1200W
100 Reviews
Skar Audio RP-1200.1D Monoblock Class D MOSFET Amplifier with Remote Subwoofer Level Control, 1200W
  • Class D MOSFET Monoblock Power Amplifier
  • Peak Power at 1 Ohm: 1,600 Watts | RMS Power at 1 Ohm: 1,200 Watts
  • Frequency Response: 20Hz - 250Hz, On-board Bass EQ Switch with +6 or...
  • Featuring 4-Way Protection Circuitry and 4 Gauge Power & Ground Input...
  • Stable at 1 ohm | Remote Subwoofer Level Control Included

The Skar Audio RP-1200.1D is nothing short of a powerhouse, considering it can output a maximum RMS of 1200 watts. This is due to the fact the unit is 1 ohm-stable, which is as low as you can get in terms of impedance. Most amps would be unstable at 1 ohm but that’s simply not the case with the RP-1200.1D. Thanks to its Class D circuitry the amount of heat generated is minimized.


The RP-1200.1D comes with built-in heat sinks that are designed to draw heat away from the internal components.

This means that the circuits won’t suffer any heat damage with prolonged use. The amplifier also features In addition, the amplifier features 4-way protection circuitry that prevents damage resulting from overheating, low voltage, electrical shortages…etc.

Bass EQ Switch

This is essentially a boost that lets you increase the volume of all signals with a frequency of 45Hz. If you feel like the low-end coming out of your subwoofers lack ‘attack’, you can boost the sub-bass up by a maximum of 12 dB.

Variable Low-Pass Filters

Low-pass filters are essentially tools for shaping your tone. They let you set a cut-off frequency and block any signals that are higher in pitch. This can help you dial out any distortion in the upper-bass regions. The low-pass filter that you get with the Skar Audio RP-1200.1D is adjustable, allowing you to set the cut off frequency anywhere between 50 Hz to 220 Hz.

Subsonic Filter

High-pass filters do the exact opposite of low-pass ones. They block signals that are lower in frequency than the cutoff pass through while allowing ones that are higher to pass through. Subsonic filters are essentially high pass filters that are restricted to bass frequencies. In the case of the Skar Audio RP-1200.1D, the subsonic filter has a set cut-off at 50 Hz.


  • High-powered
  • Built-in heat sinks and protection circuitry prevent heat damage
  • Bass EQ Switch helps to boost up the low-end
  • Low-pass and subsonic filters


  • At 7.2 pounds it’s a little bit heavy

Boss Audio Systems R1100m

BOSS Audio Systems R1100M Monoblock Car Amplifier - 1100 Watts Max Power, 2/4 Ohm Stable, Class A/B,...
3,649 Reviews
BOSS Audio Systems R1100M Monoblock Car Amplifier - 1100 Watts Max Power, 2/4 Ohm Stable, Class A/B,...
  • POWER: Maximum Power Output of 1100 Watts at 2 Ohms into one channel....
  • HIGH LEVEL INPUTS: Speaker level inputs are commonly referred to as...
  • LOW LEVEL INPUTS: Line level inputs, also known as RCA inputs or...
  • LOW-PASS CROSSOVER: A low-pass filter is an electronic circuit that...
  • VARIABLE BASS BOOST: Variable Bass Boost allows you to adjust the low...
Tons of Power

At the lowest impedance setting of 2 ohms, the R1100M has an RMS rating of 825 watts. While not quite as high as the Skar Audio RP-1200.1D, this Class A/B amplifier has more than enough to power the most demanding subs on the market.

Variable Low-Pass Filter

The R1100M’s low-pass filter is configurable between 35Hz to 160Hz, which is quite good for cleaning up any wanted distortion in the upper-bass region.

Bass Boost

If you feel like the low-end in your music is a bit lacking, then a bass boost can certainly help. The R1100M’s boost is variable, allowing you to add up to 18dB in volume to the low-end. I often found myself using the boost whenever I was listening to EDM. It can really help give those low, thumping bits some depth and make them more prominent in the mix.

Variable Gain Control

The gain control helps you balance the amplifier’s output with the sub’s input. By dialing out excess gain, you’ll prevent distortion of the signal. Otherwise, you may have to deal with clipping, which is when the audio signal becomes too large to reproduce, resulting in a lot of white noise.

Subwoofer Level Control

The R1100M comes with a wired remote that lets you easily manipulate the subwoofer level to your liking. This allows you to tweak on the fly until you’ve got the right amount of low end in your mix.

Short Protection

The R1100M’s circuit is equipped with thermal sensors that continuously monitor the internal temperature. The instant things get too hot then the circuits shut down automatically preventing any heat damage to the internal components.


  • High RMS rating
  • Variable Low-pass filter and bass boost
  • Variable gain control for cleaning up the signal
  • Remote subwoofer control
  • Short protection


  • I’m having trouble thinking of any

Rockford Fosgate R500x1d

Rockford Fosgate R500X1D Prime 1-Channel Class D Amplifier
1,404 Reviews
Rockford Fosgate R500X1D Prime 1-Channel Class D Amplifier
  • 300 Watts x 1 @ 4-Ohms, 500 Watts x 1 @ 2-Ohms, Frequency 20Hz to...
  • Onboard 12dB/octave LP/HP/AP crossover & Infrasonic filter. Power Wire...
  • On-board Punch EQ with +18dB boost at 45Hz. Input Sensitivity: 150 mV...
  • Cast Aluminum Heatsink with Stealth top mounted control panel
  • Includes wired remote (Punch Level Control). High efficiency amplifier...

At the default impedance setting of 4 ohms, the R500X1D is able to output 300 watts RMS. This by itself is quite enough to power a decently-powerful sub. However, if you require more power, simply toggle the impedance down to 2 ohms and you’ve got yourself an amplifier that can output 500 watts on the regular.

Variable Low-Pass Filter

The R500X1D’s low-pass filter works just like what you’d find on the RP-1200.1D and the R1100M. Its cutoff is adjustable between 50 Hz to 250 Hz.

Variable Bass-Boost

If you’re someone who listens to a lot of EDM, a bass boost is a useful tool. The R500X1D’s targets the 45 Hz frequency specifically which sits within the sub-bass range. It allows you to boost up these signals by up to 12dB, giving the low-end a bit more impact.


The R500X1D sports a heavy cast aluminium chassis which tends to absorb heat, directing it away from the circuit components. Hence, the internal environment will remain relatively cool even with continuous use. The circuits are fitted with thermal sensors which will switch off the unit if the temperature gets too high, hence protecting it from variations in resistance, speaker failures and other electrical issues.


  • Decent-enough power output for most subs on the market
  • Variable low-pass filter and bass-boost
  • Heat-tolerant
  • Protected against shorts and other electrical issues


  • Not the most powerful amplifier out there

Planet Audio Pl3000.1d

Planet Audio PL3000.1D Class D Car Amplifier - 3000 Watts, 1 Ohm Stable, Digital, Monoblock, Mosfet...
513 Reviews
Planet Audio PL3000.1D Class D Car Amplifier - 3000 Watts, 1 Ohm Stable, Digital, Monoblock, Mosfet...
  • Power - 3000 Watts Max x 1 @1-Ohm, 1500 Watts Max x 1 @2-Ohms
  • Class D - Power loss is significantly reduced making the amplifier...
  • 1 Ohm Stable - Able to continuously power loads of 1 Ohm without...
  • Strapping Capable - You are able to strap TWO PL3000.1D amplifiers and...
  • Variable Subsonic Filter - To prevent your subwoofer(s) from bottoming...
1-Ohm Stable

Just like the Skar Audio RP-1200.1D, the Planet Audio PL3000.1D can be switched to a 1-ohm setting without any issues with overheating. This is largely thanks to its highly efficient Class D circuit. At 1 ohm, the amplifier is quite powerful with an RMS rating of 2250 Watts. This is more than enough to power any subwoofer in the market.

Variable Low-Pass And Subsonic Filters

The low-pass and subsonic filters found in PL3000.1D help to gate higher- and lower-pitched frequencies respectively. The low-pass filter allows you to set the cut-off between 50 Hz to 250 Hz while the subsonic filter works within the range of 15 Hz to 40 Hz.

Bass Boost

The PL3000.1D’s bass boost worked exactly like the ones found in the other amplifiers. It’s adjustable, allowing you to specify how much you want to spike the volume in the low-end.

Variable Gain Control

The variable gain control helps clean up the signal that is sent to your speakers or head unit. With a little bit of tweaking, you can dial out any additional distortion.

Thermal Protection Circuit

Thermal sensors in the PL3000.1D will immediately detect large spikes in the internal temperature and switch off the unit before any damage is done. The circuit can also detect electrical shortages due to speaker failures, whereafter it will cut the output of the amplifier until the short is taken care of.


  • 1-Ohm Stable
  • The most powerful amplifier on the list
  • Variable low-pass filter, bass boost and gain control
  • Thermal protection circuit


  • There don’t seem to be any

Kenwood KAC-9106D

Kenwood KAC-9106D 2000W Monoblock Class D Car Audio Power Amplifier
208 Reviews
Kenwood KAC-9106D 2000W Monoblock Class D Car Audio Power Amplifier
  • Mono subwoofer amplifier
  • 500 watts RMS x 1 at 4 ohms (1, 000 watts x 1 at 2 ohms)
  • Class D amp design
  • Speaker-level inputs with signal Sensing turn-on
  • Variable low-pass filter (50-200 Hz at 24 dB per octave)
High Rms Rating

The KAC-9106D has two impedance settings: 4 ohms and 2 ohms. At 4 ohms, the amplifier outputs 500 watts RMS while at 2 ohms, this value doubles to 1000 watts.

Variable Low-Pass And Subsonic Filters

The KAC-9106D’s low-pass filter lets you set the cutoff frequency anywhere between 50 Hz to 200 Hz. Personally, I found myself using it to dial out the excessive distortion in the upper-bass regions. The amplifier also features a subsonic filter which operates in the frequency range between 20 Hz to 50 Hz.

Bass Boost

The KAC-9106D’s bass boost focuses specifically on signals at the 40 Hz frequency (sub-bass), allowing you to increase their volumes by up to 18dB. This allows you to ‘fatten’ up the extreme-low end so you can ‘feel’ it and much as hear it.


The KAC-9106D features a cast aluminium heat sink design which is especially great at conducting heat. Hence if any excess heat is produced (as you can often expect with prolonged use) these sinks will absorb the heat, preventing any damage to the internal components.


  • 1000 watts Maximum RMS
  • Variable low-pass and subsonic filters
  • Cast aluminium heat sinks
  • Bass boost


  • Not as feature-rich as most of the amplifiers on this list

The Best Overall

The hardest part of this whole endeavour was choosing my overall favourite out of the top five. This was largely because all the picks were excellent, featuring a variety of control, tons of power and solid builds. However, after a lot of thought, I finally arrived at a decision: the BOSS Audio Systems R1100M. My reasons were quite simple:

First of all, the amplifier had an RMS rating of 825 watts at its lowest impedance setting, which was more than enough for the subwoofer I own. The variable low-pass filter helped clean up distortion in the upper-bass spectrum while the bass boost added tons of ‘punch’ to the low-end. The variable gain control was often handy too, allowing to prevent audio clipping with just a little bit of tweaking. Finally, the amplifier featured short and heat protection features in its circuit which meant that I never had to worry about heat damage.

Frequently Asked Questions

What Is The Difference Between Mono And Stereo Amplifiers?

These terms typically refer to amplifier connections. A stereo amplifier has two independent channels which carry the left and right audio signals separately. Hence you can send each signal separately to two speakers. This makes for better panning of the instruments in music. On the other hand, mono amplifiers have a single channel which carries both the left and right signals together.

Can You Bridge A Mono Amp?

Bridging an amplifier involves consolidating the power of multiple channels into one. Since mono amps only have one channel, bridging is not possible. However, amps like the Planet Audio PL3000.1D can be ‘strapped’ which means they can be linked up with another compatible unit in order to output double the power.

Can I Wire 2 Subs To A Mono Amp?

You can do this using a few simple tools. First, cut two lengths of speaker wire. Make sure that one is long enough to extend from the amp to one subwoofer and the other is long enough to connect the two subs. Strip the insulation off the tips of the wires so that half an inch is exposed on each lead.

Take the first length of wire and connect one end to the speaker output terminals found in the amp. Then connect the positive and negative lead to the positive and negative terminals. Next, connect the other end of the same wire to the same terminals. Finally, take the second length of wire and connect its leads to the same set of terminals on the subwoofer.

What Gauge Of Speaker Wire Should I Use For A Subwoofer?

16-gauge speaker wires work well for most cases. However, if your subwoofer has an RMS rating of more than 1000 watts, then it’s best to go for a 12-gauge wire in my opinion.

The products featured on this page were last updated on 2020-03-06 at 19:42 /. Affiliate links / Images from Amazon Product Advertising API.

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