Sony Xplod XM-4S

Slim Series 4-channel car amplifier
50 watts RMS x 4

  • Sony Xplod XM-4S

    Front-without trim panel

  • Sony Xplod XM-4S


  • Sony Xplod XM-4S

    Side with trim panel

  • Sony Xplod XM-4S

    Top-with trim panel

  • Sony Xplod XM-4S

    Trim panel

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Item #: 158XM4S

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Our take on the Sony Xplod XM-4S

by Buck Pomerantz

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.

Sony designed the Slim Series XM-4S amplifier for small vehicle installations, with a low profile that allows it to fit under most front seats. On the outside, the sleek inverted heat sink keeps vital internal components running cooler and lasting longer. Removable terminal covers keep all the wire connections protected and out of sight for a clean-looking installation.

Underneath the hood, the XM-4S amplifier delivers 50 watts RMS to four 4-ohm speakers — plenty of power for even the most demanding speaker system. Or you can bridge your XM-4S into 3-channel mode, sending 50 watts RMS of power to two speakers while driving a subwoofer with 120 watts RMS from the rear channel.

Read more

You can use the high-pass filter to tailor the signal going to your front speakers, or adjust rear-channel output with the low-pass filter and bass boost. Signal-sensing speaker-level inputs activate the amp automatically when it's connected to a factory radio, so there's no remote turn-on lead for you to install.


  • 4-channel car amplifier
  • 50 watts RMS x 4 at 4 ohms (60 watts RMS x 4 at 2 ohms)
  • 50 x 2 watts RMS + 120 x 1 watts RMS power bridged output at 4-ohms (4-ohm stable in bridged mode)
  • 4- or 3-channel output (no 2-channel output)
  • CEA-2006 compliant
  • switchable high-pass filter on front two channels (80 Hz, -12 dB/octave)
  • switchable low-pass filter on rear two channels (80 Hz, -18dB/octave)
  • variable bass boost on rear two channels (0-10 dB at 40 Hz)
  • speaker-level inputs with high-level sensing turn-on
  • preamp-level inputs
  • MOSFET power supply
  • fuse rating: 40A x 1
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 8-1/8"W x 1-3/4"H x 8-13/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
RMS Power Output (Watts x Channels) 50 x 4
Peak Power Output (Watts x Channels) 95 x 4
Power at 2 Ohms (Watts x Channels) 60 x 4
Bridged Power (Watts x Channels) 120 x 2 (rear only)
Minimum Impedance Bridged 4
Minimum Impedance Unbridged 2
Best Frequency Response 5-100k Hz
THD at Rated RMS Power 1%
Signal to Noise Ratio 90 dB
Input Voltage 14.4v
Amplifier Class D
Low-Pass Crossover Frequency 80 Hz
Low-Pass Slope (dB/octave) 18 dB
High-Pass Crossover Frequency 80 Hz
High-Pass Slope (dB/octave) 12 dB
Bass Boost 0-10 dB
Bass Boost Frequency 40 Hz
Fan Cooled No
Fuse Rating 40
Speaker Level Inputs Harness
Preamp Outputs No
Width (inches) 8-1/8
Height (inches) 1-3/4
Depth (inches) 8-13/16
Parts Warranty 1 Year
Labor Warranty 1 Year
Product Research
What's in the box?

Download owner's manual

  • 4-channel amplifier with one 40-amp ATO fuse inserted into the chassis
  • 8" Speaker-level input harness (with 8-pin Molex plug on one end)
  • 4 Philips-head mounting screws
  • Operating instructions (English/French/Spanish)
  • Warranty sheet

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 open the box, verify contents, 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.

Inputs and Outputs Notes


Slim-Line Design: The Sony amplifier's slim, low-profile design allows it to work under many driver, passenger and rear seats of vehicles.

CEA-2006 Compliant: The Sony amplifier is CEA-2006 compliant with a rating of 50 Watts x 4-channels in 4 ohms between 20 to 20,000 Hz at 1% THD+N with a signal-to-noise ratio of 90 dBA.

Class D Technology: The Sony XM-4S uses Class D Technology to covert and amplify music signals with MOSFETs to high speed pulse signals. This type of amplifier design features high efficiency and low heat generation.

Pulse Power Supply: The amplifier utilizes a light-weight Pulse Power Supply system for stable and regulated output power. This highly efficient design helps regulate fluctuating voltage from your car's battery while maintaining a low impedance output.

4/3 Channel Amplifier: The Sony XM-4S is a 4-channel amplifier that is capable of powering four full-range speakers or the rear channels can be bridged for a 3-channel configuration. In 3-channel mode the amplifier's front channels remain stereo while the rear channels are bridged down to a mono-channel output. The amplifier has a maximum rating of 95 watts x 2 + 250 watts x 1 at 4ohms in 3-channel mode.

Note: The front channels of this amplifier are not bridgeable.

Gain Control: The amplifier features independent gain control for the front and rear channels.

High Pass Filter: The amplifier features an 80Hz, 12 dB per octave high-pass crossover for the front channels.

Low Pass Filter: The amplifier features an 80Hz, 18db per octave low-pass crossover for the rear channels.

Low Boost Circuit: The amp also features a variable Bass boost which can be adjusted from 0 to +10dB at frequencies of 40 Hz that only effects the rear channels of the amplifier.

Hi-Level Input: The amplifier features a Hi-Level speaker input for connecting the amplifier to your factory or aftermarket stereo that does not use RCA outputs. The amp also is equipped with a Hi-Level Sensing Power On feature that allows the unit to be activated without need for the Remote turn-on connection when using the Hi-Level input.

Active Thermal Control: The Active Thermal Control regulates the unit's operating temperature for stable, long-term playback at high volume. The amp will restrict maximum output due to high temperature irregularities.

Protection Circuit: The XM-4S amplifier features a protection circuit and indicator in case of a short circuit or bad ground.

Blue Illumination: The amplifier features two Blue LEDs that can be turned On or Off. These Blue LEDs will light up the foot area of your car when the amplifier is mounted under a seat.

Inputs and Outputs Notes

Removable Top Surround: All of the amplifier's connections are located on the front side of the amplifier to make installation and connection simpler. To access the speaker, ground and power terminals you must remove the top chrome surround which is attached by 4 phillips-head screws. Once the chrome surround is reinstalled it protects the amplifier's terminals from being contacted by other items in your vehicle. The amplifier features the following inputs and outputs.

  • Power/Ground Terminals: The power and ground screw terminals are 0.375" wide to easily accommodate 8-gauge wire.
  • Remote Turn-On Terminal: The Remote Turn-On lead screw terminal is 0.375" wide to accommodate 8-gauge wire.
  • Speaker Terminals: The amplifier features four pair of 0.375" wide speaker terminals.
  • Speaker-level Input Harness: The amp comes with a 4-channel speaker-level input harness with an 8-pin Molex plug on one end. This allows you to more easily connect this amplifier to a factory deck or a receiver without preamp outputs.
  • RCA Input: The XM-4S is equipped with a two sets of Stereo RCA inputs for connection of your aftermarket stereo to the amplifier.
  • Fuse: The amplifier is equipped with one 40-amp blade fuse.
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Sony Xplod XM-4S Reviews

Average Customer Review:

15 people say:

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5 out of 5

so right

Written By ricky, Elgin, IL on Friday, October 19, 2012
I had high hopes. At first i thought my excelon head was better. But after tuning and putting in great speakers. All i can say is wow! You can really hear every pop crackle and bang in the music. Got alpine 6.5s in front and rockford 6/9s in back. You can hear the breathing in voices and no distortion. The sony amp is perfect.
Awesome tunability. Small size. Sweet power.
None. Put some 50rms, 200max watt speakers on this and you will be in heaven.
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5 out of 5

Little amp, big sound

Written By Bob W, St Louis, MO on Sunday, April 15, 2012
Crutchfield Customer Review (What's this?)
Had a serious space constraint, small car (Honda Fit) but wanted/needed more power than any head unit can produce. Was pretty sure it would drive a pair of Focal Polyglass components, but wasn't sure that the other two channels (bridged) would drive the Infinity 10" sub. Turned it on and was quite surprised and pleased. Filled the car with sound.
Small, but still has some cahonies.
None that I have seen yet.
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1 out of 5

Pathetic Warranty Service

Written By Bob, Ann Arbor, MI on Wednesday, September 30, 2009
Crutchfield Customer Review (What's this?)
Installed this Amp and the sound was great... for about a week. Then it completely fried for no reason while playing classical music at soft volume. Crutchfield referred me to Sony, and I've never had a worse warranty experience in my life. Nice amp if it works, but don't expect anything for warranty service.
4 out of 4 people found this helpful
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5 out of 5

Beautiful Music

Written By logan, Cincinnati, Ohio on Monday, August 31, 2009
Crutchfield Customer Review (What's this?)
Very nice looking and powerful amplifier. Mounted in an '03 tiburon powering componants up front and 6x9s in the rear. Very clear sound and plenty of punch. Would buy this amp again.
1 out of 1 people found this helpful
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5 out of 5

Great little amp

Written By Paul, San Diego, CA on Wednesday, August 12, 2009
This baby works very nice. I'm pushing a pair of Infinity 5020CS on the front and the rear channels are bridged to a JBL GTO804 in a sealed enclosure. The bass is tight and goes down w/o problem, mids and highs soung clear and good detail. I did use an oscilloscope to match the output of my Eclipse CD5030 to the input of this amp, and I can go almost all the way up in the volume w/o distortion. Very small footprint, I have it under the driver seat of Tacoma 01; it does get a little hot to the touch but the amp has a built-in fan. Nicely done Sony!
1 out of 1 people found this helpful
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5 out of 5

2003 Chrysler Sebring Convertible

Written By Alex M, Fairfax, VA on Wednesday, June 17, 2009
This amazing amp fits perfectly in the factory location of my old Infinity amp. It
powers my two sets of Polk Audio db5251with incredible precision and
accuracy. I never thought that my Polks sound amazing until I purchased this
amp. If you have a car with limited space, you should definitely buy it.
1 out of 1 people found this helpful
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5 out of 5

2004 BMW 330Ci

Written By Randall, NC on Sunday, May 03, 2009
Crutchfield Customer Review (What's this?)
A very clean amp that is small enough that it can fit in locations other amps won't. Driving Polk Audio 5.25" component set in the front and 6.5" component set in the rear. The music is awesome.

This is the third amp of this model that I've bought and I recommend it to friends.
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5 out of 5

Works great looks great, just smaller.

Written By Charles, Topeka, KS on Monday, August 25, 2008
Works great, no excess anything, including size. Looks good enough to not mount stealth. Cannot find anything to criticize about sound.
2 out of 4 people found this helpful
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5 out of 5

very nice

Written By Sam, WV on Friday, April 18, 2008
This amp is great. Very small in size so it will fit almost anywhere. Installed it in an '06 colorado crew cab on 1/2" board and still fits under the seat with room to spare. powers 4 polk audio 6 1/2's with ease.
8 out of 9 people found this helpful
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5 out of 5

Amazing amp!!!!!

Written By Robert, Delaware on Saturday, March 01, 2008
I purchased this amp about a month ago. I have it running Infinity Reference 6-1/2" components up front and Infinity Reference 6-1/2" shallow mount coaxials in the rear of a 2006 Kia Sorento. I am HIGHLY impressed by the way the amp effortlessly pushes them!!!!! My installer was equally impressed with the performance AND size of the amp! He said that he will use this little amp whenever he has an install where space is an issue. I HIGHLY recommened this amp.....a GREAT buy! WAY TO GO SONY!!!!!!!!!!!
7 out of 7 people found this helpful
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5 out of 5

Great Amp in a tiny package!

Written By WeeHooker, SE Mass on Sunday, July 29, 2007
When I decided to go ¡§whole hog¡¨ and include a amp into the system upgrade for my new Nissan Frontier Crew Cab, I got quickly amazed at the physical size of most 4 channel amps. ( How is it they can put 200W amps into the leftover space of any single din head unit but a 400-500W amp requires a that it be as big as a toaster oven??) If I was going to stuff an amp into my compact 4 door truck , it was going to have to fit under he passenger seat or against the back bulkhead. Neither had much roomƒ¼ Enter the new Sony XM-4S amp. Just what I needed to drive my new 60-75W RMS Polk and Infinity speaker sets. . It delivers a full 50W RMS x 4 channels out of a thin, 8x9¡¨package and doesn¡¦t seem to give up anything. My buddy (a professional audio installer) was also initially impressed with it¡¦s size and latter commented at it¡¦s performance and quietness. All I know is that it fit fine ( rear bulkhead, behind the seat), and it sounds great!
11 out of 12 people found this helpful
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5 out of 5

Great for the problem install

Written By David, Arlington, VA on Tuesday, May 29, 2007
I cannot recommend this amp enough. When nothing else works, this amp fits anywhere. It is the smallest model on the market. I had no space in my SUV, and this amp fits perfectly under my front seats. I matched this with the Sony XM-1S, and my car sounds great.

This is a quiet, cool amp that produces clean sound. You may get more power for the money, but there is more than enough here make my door speakers come alive. I cannot believe how much more clear and precise my stereo sounds now over my head unit that produced 45 watts RMS.
5 out of 7 people found this helpful
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5 out of 5


Written By Jim, Memphis, TN on Wednesday, April 25, 2007
Crutchfield Customer Review (What's this?)
This amp is floor mounted in the center under the rear seat of an extended cab GMC truck. Plenty of room, easy install with just a power(w/ fuse) and a ground cable(both purchased separately). I bought this particular amp for the "hi-level sensing power" feature. The amp is connected ONLY to the speaker wires(+ power & ground)which is cool! The only thing I needed help with was the color codes of the factory speaker wires which I found on the internet. Was just running with stock type speakers until I remembered some 13+ year old Krunch boxes I had. Just layed them under each side of the rear seat and now have PLENTY of base. It can all be taken out quickly if the seat needs to be raised for hauling something inside.
4 out of 4 people found this helpful
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4 out of 5

Nice and Small

Written By Bill, Mount Airy, MD on Friday, April 20, 2007
I bought this amplifier to power 4 infinity kappa 6.5" speakers in my Saturn Ion. It's slim design is nice and I have no problems with the gain set pretty high.
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5 out of 5

Compact Power

Written By Kevin, Carrizo Springs, TX on Tuesday, March 20, 2007
Crutchfield Customer Review (What's this?)
The compact design makes the XM-4S easy to hide away while providing the power to make it loud.
7 out of 11 people found this helpful
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You'll need an amp wiring kit to install your new amplifier, as wiring is not included. See all categories & accessories

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For a more in-depth review and enhanced detailed information on the Sony Xplod XM-4S, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_158XM4S/Sony-Xplod-XM-4S.html ).