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Digital technology that sounds perfect

Alpine's X-Power MRX-M55 mono amplifier uses the latest amp technology to play your music loud and clean without taking up much space. And this amp employs some of the same circuitry developed for Alpine's top-of-the-line PDX digital amps, so it'll bring exceptional sound to almost any ride.

Big power for big bass

The MRX-M55 puts out up to 550 watts RMS to your subwoofer system, so you can fill your listening space with plenty of bass. And it'll even operate safely with a 1-ohm load, making it useful in a variety of sub system installations. Onboard low-pass and subsonic filters let you get the best sound out of your setup, while a bass boost helps to fatten up the sound if you need it.

Keep the music playing

A power management system optimizes the amp's performance and keeps the music playing, even when you're pushing it hot and hard for a long time. Speaker-level inputs with an automatic turn-on feature simplify system hook-up.

MRX-M55 control panel

Product Highlights:

  • mono subwoofer car amplifier
  • 350 watts RMS x 1 at 4 ohms (550 watts RMS x 1 at 2 ohms)
  • 400 watts RMS x 1 at 1 ohm
  • CEA-2006 compliant
  • variable low-pass filter (50-400 Hz, 24 dB/octave)
  • variable bass boost (0-12 dB at 50 Hz)
  • variable subsonic filter (5-30 Hz, 24 dB/octave)
  • optional remote level control (RUX-KNOB)
  • Class D amp with MOSFET power supply
  • preamp and speaker-level inputs
  • preamp outputs
  • fuse rating: 30A x 2
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 9-15/16"W x 2-5/16"H x 9-1/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Alpine MRX-M55 Reviews

Average Customer Review:

25 reviews
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Great amp!

Written By Jay, Colorado on Friday, February 27, 2015

Crutchfield Customer Review (What's this?)

Great amp! Setup was simple, runs cool, and does everything I need it to do. Running a single 12" sub currently, no issues whatsoever.

Pros: Everything. I just needed a good mono amp to push a ~300 rms 12" sub, and it does so perfectly. Having both low pass and subsonic filters lets me dial in the exact range I want to work in.

Cons: None, really. Very solid choice if you need a moderately-powered amp!

Excellent Amp

Written By Chris, New Jersey on Monday, December 29, 2014

Crutchfield Customer Review (What's this?)

Hi all. bought this to replace a several year old Kicker Ix500.1. Using the Same Subwoofer (JL W3v3 2Ohm Sealed box), Its like Day and Night. The Subwoofer seemed to wake up. Just need to Tweak it. And don't know Why, Alpine used Aluminum Wires on the Speaker Level Input?? Made a but tricky to solder the connections.

Pros: Good Size. Powerful. Speaker Level Input (Factory HU). Tested at 578 Watts RMS (2ohm)

Cons: Aluminum Speaker Input leads?? No Remote Lead output. Cant activate the voltmeter on my capacitor until I run another wire.

alpine amp

Written By Bigdumy, New Jersey on Saturday, December 20, 2014

Crutchfield Customer Review (What's this?)

the best of the rest... clarity is what I strive for, and it is what I got from alpine... awesome amp, loud, and easy to connect... BUY IT!!!!

Pros: best

Cons: none

delivers the power

Written By Dan, Vermont on Wednesday, December 17, 2014

Crutchfield Customer Review (What's this?)

Does what it is supposed to


Written By Kyle, Apo,Ae on Monday, December 08, 2014

Crutchfield Customer Review (What's this?)

Tons of power bought two of these to power my two ten inch subs and man do they hit deeper and have such a better tone to them then my previous amp did. I haven't even had a chance to properly tune them yet due to the fact I just got in my new mids and highs in the mail today!

Pros: Very smelly and compact pack one hell of a punch!

Cons: None simply amazing

Perfect Match

Written By Justin J., Newport News, Va on Monday, November 24, 2014

Crutchfield Customer Review (What's this?)

Got this to round out my system in my 04 TL. It's running a single sws-12d4 in a sealed box beside a mrx-f35 and polk dxi components. Wiring was easy, and setup is flexible letting me dial in just the right ammount of thump. Rated power is 609watts @ 2 ohms. Running the sub @ 2ohms i get impressive response and tight control. This is my first system to use a sub but it's my 3rd Alpine amp. Didn't even consider anything else. For an enthusiast (not a competition or "audiophile" grade) system I couldn't be happier.

Pros: Small footprint, great power, cool running and responsive

Cons: Can't think of one.

Always loved alpine

Written By Joe, Holly, mi on Sunday, November 23, 2014

Crutchfield Customer Review (What's this?)

This amp is great. Have it pushing a 10" mb quart at about 375 rms (guessing) at 1 ohm and its pretty loud! Gives enough power to play heavy bass songs with ease. gain set to about an eighth of the way. Gunna hook it up to a type s (12d2) that takes 500w RMS at 1 ohm and i know it will preform well. I have never found a brand in this price range to beat alpine. There stuff is perfect for almost anyone. Trust this brand and the crutchfield staff!

Pros: Powerful, very small, blue led looks sweet in trunk, easy to install and tune

Cons: So far none

mrp m500

Written By leroy, mississippi on Wednesday, November 19, 2014

i have the alpine mrp m500 hooked to a pair of champion series pioneer 12s in sealed box.....for a while it bumped so hard it would knock the wind out your ears and this was when the radio on 15 and the amp half way...after a month they sound like 10s...subs wasnt blown no wires lose....guess i broke em in.....but i put in my focus wagon they sound like 15s....mayby i need to go bigger in my magnum

Pros: mrp m 500 sound good with 2 12in pioneer champion series in 2014 focus wagon

Cons: imma have to go with a bigger alpine and subs for my magnum...i shoulda kept my mtx 1000.1d for the magnum

Alpine MRX-M55

Written By Justin, San Antonio, Tx on Monday, November 17, 2014

Crutchfield Customer Review (What's this?)

Great Bass. Great Customer Service

Great Amp (If Yours Doesn't Have Problems)

Written By Brad, Northern VA on Thursday, October 30, 2014

Crutchfield Customer Review (What's this?)

  • "Coolness Factor"
  • Build Quality
  • Ease of Use
  • Sound Quality
  • Value

I would like to preface this review by saying that if you get one of these amps and it functions correctly, then you will be a very happy consumer. It looks great, installs easily, and has some nice features. My story (I'll give you the short version) has not been so nice.

The first amp I received was broken right out of the box (knobs would spin infinitely). Crutchfield replaced that, no problem (best customer service). A few weeks later, the bass would randomly start cutting out while I was driving. I spent weeks looking into BT issues with my car and phone, troubleshooting power and ground to the amp, and looking into various causes with Cruthfield techs. In the end, I was told that I most-likely have a defective amp and need to contact Alpine. Call Alpine and you have to pay to send them the amp, they will "test" it and send it back fixed (or new if unfixable). So, I'm now riding around with no bass (again) after purchasing this amp at full price (it wasn't on sale when I bought it). I'm sure they're going to send the amp back as-is because they won't be able to replicate my intermittent problem, and I'm going to toss it straight in the trash. Take this review with whatever amount of salt you feel is necessary, but I have had a horrible experience with Alpine electronics (used to be my go-to amp company) and I will have to think very hard before I buy something from them again.

Pros: Sleek Looks Small Size Features (subsonic filter, speaker-level inputs, etc)

Cons: Horrible Alpine Customer Service Terrible Build Quality

Great amp

Written By DeKees1, Tampa fl on Wednesday, October 22, 2014

I have this amp runnin my 10in alpine sub and it hits hard and sounds so clean in my 06 Vw rabbit. Haven't had any issues with it in the last almost year now.

Power house

Written By Jimmy, Greenfield on Wednesday, October 08, 2014

Crutchfield Customer Review (What's this?)

Small size but powerful amp , very reliable, I travel for hours daily and have the tunes going the whole time .

Pros: Compact size , very powerful , tons of adjustment .

Cons: None

Excellent for driving my 10"

Written By Samuel L, Dublin, CA on Wednesday, September 24, 2014

Crutchfield Customer Review (What's this?)

Plenty of power to drive a dual voice coil 10" in a sealed enclosure. Gain is @ 50% and it sounds great! Foot print of amp is small and easy to place in my trunk.

Pros: Efficient, great value for the money. Crutchfield advisors guided me to this amp, they where patient and answered all my questions.

Cons: none

alpine mrx m55

Written By anonymous, Somewhere, USA on Saturday, September 20, 2014

Crutchfield Customer Review (What's this?)

Good amp. No issues so far

Pros: sounds clean

Cons: None so far

Great Amp

Written By joshua L, corpus christi, TX on Sunday, August 31, 2014

Crutchfield Customer Review (What's this?)

Great Amp pretty small fits right under sit in a 09 Silverado single cab and delivers great clean power birth sheet was 592W at 2 ohms

Pros: great size and power

Cons: none

Great amp

Written By Stephen b., Coaling on Wednesday, August 20, 2014

Crutchfield Customer Review (What's this?)

So far so good. Real nice compact size. Give you everything you need .


Written By Jack, Augusta, GA on Wednesday, July 02, 2014

Crutchfield Customer Review (What's this?)

Great amp. It's paired with a 10" R series sub, and it hits hard and tight.

Pros: Crossover and eq adjustments


Written By kungfucious, Carlsbad, CA on Saturday, June 28, 2014

Crutchfield Customer Review (What's this?)

Works perfect, big power, small amp :-)

Power to the sub

Written By RMJ, Fredericksburg,VA on Tuesday, June 24, 2014

This amp give the sub that awesome kick so you know it's there.

Pros: Neat little powerhouse.

Cons: None


Written By Jodyd, Louisiana on Tuesday, October 22, 2013

Crutchfield Customer Review (What's this?)

I bought this amp to replace my alpine mrp-m500 (a friend wanted to buy it from me). It has a little more power not sure if it's dramatically more though. It plays very clear. It is definitely an upgrade do to the ability of being able to add a remote, the subsonic setting, and 50 more rms watts. The size is also smaller, I was very surprised when I unboxed it. I have it pushing an alpine type r 10" in a ported box in my 2012 super crew f150. I'm definitely under powering the sub but it still sounds awesome clean sound go alpine!

Pros: Small, powerful, flexibility in settings

Cons: None

more then enough!!

Written By Mark H, Cincinnati, OH on Tuesday, September 17, 2013

Crutchfield Customer Review (What's this?)

I purchased 2 of these for 3 subs. 2 10in dvc for 1 and being 1ohm stable makes for great power to feed these subs.They've never hit so hard. And the other amp i purchased with the seprate gain contol knob to feed 1 400w dvc. All subs are JBL. there is no substitute. Very impressed with both amps.Neither 1 runs hot. customer service with brooke was great. She even tryed to save me money.

Pros: Very powerful. Like the connection style better then the older models. Makes for easier and cleaner install.

Cons: Its not really a con nor a complaint. but when buying 2 of the same amps. The date of birth on 1 says 595 watts and the other says 623 watts. its just one of those odd and curious whys? but it does also say 550min.

606 watts @ 2ohms birth sheet

Written By bman, OK on Friday, April 26, 2013

Crutchfield Customer Review (What's this?)

Easy install and setup. Only pushing a single DVC 10" Stype and it doesn't break a sweat.

Pros: plenty of power

Cons: none so far

it pounds

Written By badboyb, Given, WV on Monday, April 22, 2013

Crutchfield Customer Review (What's this?)

This amp will handle pushing dvc subs and is 1 ohm stable ! Nice

Pros: Easy to hook up.

575rms@2ohm birth sheet

Written By meNurma, ohio on Monday, July 02, 2012

Crutchfield Customer Review (What's this?)

as title states birth sheet claims 575rms @2ohms thats kinda disapointing as Alpine states on there website "Each amp comes with their very own verification certificate documenting its actual power output exceeds the rating by a wide margin" Umm 25 watts more isn't a wide margin to me. I have the gain almost all the way up and also using the OPTIONAL bass knob control and it's not hitting as hard as i would like but that could be from multiple problems bad amp or just simply needs tuned better etc etc. My lights seem to not dim that much i'm running a OEM 120amp alt and a Optima yellow top as my main car battery that's it. Hooked up to one Alpine Type R 4th gen wired @2ohms in a Sound Ordnance sealed .95ft box filled with polyfill

Pros: clean power , small footprint

Cons: bass knob not included , 1 year warranty unlike other brands with 2 years in this price range

Nice Amp!

Written By Joey, Clarksville, Md on Friday, June 22, 2012

Crutchfield Customer Review (What's this?)

Very nice amp. Using this amp to power a 15" sub in a sealed box. Plenty of power to drive it. Alpine sent out a verification certificate which shows actual output power(RMS) at 630 watts at 2 ohms. Sound quality is very clean. Cool running amp also. I have had this amp only a few weeks , but so far so good...

Pros: Size, power, cost and clean sound...

Hands-on research

What's in the box?

Download owner's manual

  • Mono amplifier with two 30A fuses installed
  • Left plastic terminal cover
  • Right plastic terminal cover
  • 4 Terminal cover screws (M3 x 10mm)
  • 4 Self-tapping screws (M4 x 20mm)
  • 2.5mm Allen wrench
  • 7" Speaker-level input harness
  • Owner's Manual (Eng/ Fren/ Span)
  • Warranty sheet
  • Online registration card
  • Alpine Verification Certificate

Product Research



MRX Amplifier Design: Class-D amplifiers boast higher efficiency, produce less heat, and draw less current than traditional Class-AB amps. The MRX series benefits from the technology trickledown from Alpine's more expensive PDX amps, including Direct FET final outputs, thermal management processor, 6-Layer Glass Epoxy PC Board; combining to create a high-end sound quality without the bulky heat sinks required by most amps in this power class.

STAR Topology: Alpine's unique STAR (Signal Transit for Accurate Response) Circuit PCB design provides a single common ground for all amp sub-blocks, preventing ground interference and minimizing internal noise.

Power Management Processor: The multi-stage Power Management Processor continuously monitors component temperatures throughout the amplifier and decreases power output if anything gets too hot. When playing music under heavy loads for long periods, the circuit automatically reduces power output slightly at first, and then further in a second stage if necessary. This two stage approach provides an interruption free listening experience.

CEA 2006 Compliant: The MRX-M55's power ratings are measured according to the Consumer Electronics Association CEA-2006 standards. These standards allow you to accurately compare the rated power output of all CEA 2006-compliant amplifiers, even different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging. The power output is measured from 20 Hz to 400 Hz using a 14.4 volt power supply with no more than 0.01% THD+N:

  • 4-ohm: 350 watts
  • 2-ohm: 550 watts
  • 1-ohm: 400 watts

Signal-to-Noise: When measured under CEA-2006 conditions (reference 1 watt into a 4-ohm load) the signal to noise ratio is 90 dBA. Measured at the rated power output S/N is 114 dB.

Verification Certificate: The amplifier comes with a certificate that lists the RMS power output measured from that specific amplifier. It also lists the model number, serial number, test date, and the test conditions (voltage and impedance).

Auto Turn On: When using the speaker level inputs the X-Power amplifiers automatically turn on when voltage is detected on the signal inputs, making them an easy factory system upgrade.

Low Output Impedance: With low output impedance, the MRX-M55 outputs tightly controlled bass, with a damping Factor rated at greater than 1000.

LED: The top panel LED power indicator glows blue when the amplifier is turned on.


Gain: The MRX-M55's gain is set according to the level of the incoming signal. The line-level input gain setting is continuously variable from 100 mV to 4.0V; the speaker-level input gain setting is continuously variable from 250 mV to 10.0V.

Crossover: The low-pass crossover point is continuously variable from 50 to 400 Hz and the slope is 24 dB/oct; the crossover cannot be bypassed.

Subsonic Filter: The amp also has a 24 dB/oct subsonic filter, continuously variable from 5 to 30 Hz.

Bass EQ: Bass boost can be applied to the subwoofer output; it's variable from 0 to +12 dB and centered at 50 Hz.


Power/Ground/Remote: The MRX-M55 features set-screw terminals for the Power, Ground and Remote Turn-on inputs. The Power and Ground terminals will accommodate up to 4 gauge wire (Alpine recommends 4 gauge for cable runs over 3'), the Remote Turn-on terminal will accept up to 8 gauge wire.

Speaker Output: The speaker outputs terminal is also set-screw terminals and will accept up to 8 gauge wire.

Line Input/Output: Line level RCA is the preferred input connection. The full range stereo line output allows easily adding another amp without running a second set of cables.

Speaker Level Input: Use the included speaker level input harnesses if the connected radio has no preamp outputs.

Fuses: The amp is protected by two chassis mounted 30-amp ATO fuses.

Remote Bass Control (optional): Alpine's RUXKNOB wired remote (sold separately), connects to the amp's RJ-25 Remote Bass Control jack, and offers control of the subwoofer output level from the front of your vehicle. The linear attenuation can be adjusted from 0 to -20dB.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.