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Sony XMS400D

Compact 4-channel car amplifier — 45 watts RMS x 4

Item # 158XMS400D

Sony knows that many vehicles just don't have space for a big amplifier, so they've created the XMS400D 4-channel amp.

Read more from Crutchfield writer, Buck P.

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About the Sony XMS400D

Seriously small amp

Sony knows that many vehicles just don't have space for a big amplifier, so they've created the XMS400D 4-channel amp. This tiny powerhouse will blow your mind — blasting your front and rear speakers with 45 watts RMS each from a chassis that's the size of a big candy bar.

Seriously small amp

Sony knows that many vehicles just don't have space for a big amplifier, so they've created the XMS400D 4-channel amp. This tiny powerhouse will blow your mind — blasting your front and rear speakers with 45 watts RMS each from a chassis that's the size of a big candy bar.

High- and low-pass filters

You can't bridge this amp, but you can use the onboard switchable high- and low-pass filters to run small subs with the rear channels and full-range speakers with the front channels. The amp will accept preamp or speaker-level signals, so it'll hook up to just about any system.

Looking for bass

Got a Sony receiver with Mega Bass but no subs yet? This amp connects easily to your system, and the extra power will make your speakers sing. If you've got aftermarket speakers in your car, turn on Mega Bass and you'll hear a night-and-day difference in the bass.


Product highlights:

  • 4-channel car amplifier
  • 45 watts RMS x 4 at 4 ohms (non-bridgeable, only works with 4- to 8-ohm speakers)
  • CEA-2006 compliant
  • switchable high-pass filter on front channels (120 Hz at 12 dB/octave)
  • switchable low-pass filter on rear channels (120 Hz at 12 dB/octave)
  • preamp and speaker-level inputs
  • fuse: 15A x 1
  • 12-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • dimensions: 7-1/4"W x 1-1/2"H x 2-1/2"D
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # XMS400D

What's in the box:

  • 4-Channel amplifier (15A ATM fuse installed)
  • 8" RCA input harness (10-pin Molex plug)
  • 39" Speaker-level input harness (10-pin Molex plug)
  • 40" Power/speaker output harness
  • 2 Self-tapping screws (3/4" length)
  • 2 Mounting tabs
  • 2 Bracket screws (1/8" diam.x 1/4" length)
  • Operating Instructions
  • European Guarantee Information Document

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Customer reviews

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Sony XMS400D Reviews

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Crutchfield response

Product Research


Overview: The Sony XM-S400D is a very compact amplifier, designed for moderately sized mobile audio systems. It is ideal for amplifying front and rear speakers in a vehicle with a factory or aftermarket stereo. You can also drive small subwoofers instead of full range speakers on the rear channels. The XM-S400D is a Class D 4-channel stereo amplifier that outputs 45 watts per channel RMS at 4 ohms. It comes with RCA and high-level input harnesses, and a power/speaker output harness.

Note: The XM-S400D cannot be bridged for driving a single subwoofer.

Crossovers: The XM-S400D is equipped with a 120Hz high-pass filter (HPF) for the front channels, and a 120Hz low-pass filter (LPF) for the rear channels. The HPF will filter out low frequencies from the front channels to eliminate distortion. The LPF will filter out voices and higher frequencies from the rear channels when they are used for driving subwoofers. (The LPF should be turned off when full range speakers are connected to the rear channels.) Both crossovers have a 12dB per octave slope, and are controlled with separate on/off switches.

Input Select: The Input Select switch lets you set the amplifier to match the input connection. If you have connected the amp to one pair of inputs, the switch should be set at "2CH." All four outputs are fed the signal from the 2-channel input. If you have connected the amp with two pairs of inputs, the switch should be set to "4CH".

High-level Sensing: When the speaker-level input is used, the amplifier can sense when an audio signal is present on the input and will turn on the amplifier. The amp will automatically turn itself off when no audio signal is detected. This eliminates the need for connecting a remote turn-on wire.

Connections: The Sony XM-S400D features harnesses for all power and signal connections:

  • Power/Speaker Outputs Harness: The 40" main harness has connections for power, ground, and amp turn-on, as well as the outputs for front and rear speakers. The speaker outputs follow the industry standard color coding. The wires connected to the power and ground wires should be at least 14-gauge.
  • Fuse: The amplifier has a 15A ATM (mini-blade-type) fuse installed next to the power/speaker harness plug.
  • Input Harnesses: The amp has a 10-pin Molex receptacle for either the line-level or speaker-level input harness. The line-level harness has two pairs of female RCAs. The 39" speaker-level input harness has wires for connecting the speaker output wires from the head unit. The wires follow the industry standard color coding.

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Customer Q&A

Crutchfield asked: Why did you buy this?
Make sure the radio had enough power! [ Richard Scott  Nov 25, 2018 ]
Size. Correct output for my application. Sony reputation. Good reviews. Ease of installation and operation. [ TripleThrills  Aug 14, 2018 ]
Small, higher power than receiver, it's a Sony [ Brian  Jun 22, 2018 ]
Recommended by Crutchfield [ KYLE  Dec 05, 2017 ]
Small size. Amp power. Line input.4 Channels. [ Dale  Sep 22, 2017 ]
Small slim design for my no space need [ Daryl  Jul 20, 2017 ]
Compact size and I trust the Sony name. [ John  Jul 17, 2017 ]
Car is loud. Needed more power. Recommended by Rusty Rusty's Bio: [ R  Jul 26, 2016 ]

8 questions already asked

Under "What's in the box" it says: 40" Power/speaker output harness. When I add this amp to shopping cart, Crutchfield suggests buying an amp kit. It already has 40" of power and speaker wires, so do I need the additional wiring kit like it suggests?
[ Leonr  Feb 04, 2019 ]
3 answers
Hi, It depends on the vehicle application. In some cases it is not required.
[ BMW HUDSON  Feb 06, 2019 ]
If you up grade your stereo already, no you don't need extra wires it comes with a wire harness already. Hope this was helpful ??
[ DANIEL  Feb 06, 2019 ]
Yes, you need to buy a amp install kit.
[ Dustin  Feb 06, 2019 ]
Is this and plug and play with Sony XAV-AX5000?
[ Tom  Dec 23, 2018 ]
3 answers
Plug and play yes with the RCA Jack's, but you will still be required to supplya both a 12 switched and a 12 volt constant on supply and a negative ground. The you must still run wires for your speakers
[ John  Dec 23, 2018 ]
Hi Tom, It all depends on what you mean by plug and play. If there is a harness kit available from Crutchfield that allow you to simply plug in the speaker wires without any splicing the answer is YES! In my case, the optional harness kit plugged into the Amp and the speaker wires had to be spliced into the radio harness connector. This took all of 1/2 hour to do. Best regards, Phil D.
[ BMW HUDSON  Dec 23, 2018 ]
[ BRIAN  Dec 23, 2018 ]
Should I buy an amplifier power wiring kit for this or will this work fine with the current wiring? I have a 2003 Honda CRV EX with Sony WX-900BT.
[ Jesse  Sep 25, 2018 ]
2 answers
An amp kit is preferred for ease of installation, although most are overkill. This amp only draws 15amps so try to find something that is for a 400w amplifier so you dont need to run a very large power cable through your car.
[ Ryan  Sep 25, 2018 ]
It comes with a universal harness. If you have a plug to play option and don't like splicing wires, go that route
[ BMW HUDSON  Sep 25, 2018 ]
Will the output wires from my current Sony MEX-N5100BT stereo. plug and play directly to this amp without splicing?
[ Travis  Sep 07, 2017 ]
2 answers
No. You will have to match the color coded wires and splice them together
[ John  Sep 08, 2017 ]
You wil have to splice but super simple
[ kenneth  Sep 08, 2017 ]
Is there anyway to add a sub to it?
[ Mark  Feb 15, 2017 ]
1 answer
The rear channels of this amp has a selectable low pass filter to drive one or two subwoofers. Choose subwoofers with high efficiency since you only have 45 watts per channel to play with. A ported box will help you gain more volume as well.
[ norurb  Feb 15, 2017 ]
I want to use 2 channels and would like to know how much the nominal power (RMS) for each channel is in that case. I know that the amplifier delivers a power rating of 45 watts per channel if I use 4 channels. I want to use 2 channels and do not know whether the power for 2 channels is 2x 45 watt or 2 x 45 + 45 = 90 watts. Can someone help?
[ Davy  Aug 13, 2016 ]
1 answer
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the settings on the product and see if there may be a fix. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer. You can also post your question in our forums: Or try our online support center:
[ Krissy  Aug 15, 2016 ]  Staff

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