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Sony XM-GS400

4-channel car amplifier — 70 watts RMS x 4 (New Stock)

Item #: 158XMGS400

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5 Reviews | 1 question - 1 answer

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Brings you the music

Sony XM-GS100 330W x 1 Subwoofer Amplifier

You'll get 70 watts RMS to each of your front and rear speakers with Sony's XM-GS400 4-channel amplifier driving your system. Or you can switch the amp into 2-channel mode to power a couple of subs with 160 watts RMS each. This compact amp sports a hefty heatsink that gets rid of the heat that's generated when you're pushing your system hard. The XM-GS400 also uses a cooling fan, which automatically adjusts its speed for the heat it detects, ensuring this small amplifier will always produce the power that's expected.

More features

Sony's XM-GS100 4-channel amplifier

All connections are located on one side of the amp, which makes wiring simpler and neater. The tuning controls sit protected under a cover so they won't get inadvertently moved. You'll find separate controls for the front and rear channels on this versatile amp. You can run two speakers and a sub, for instance, and have the correct high-pass, low-pass, and subsonic filters available to get the tone right. You'll appreciate the bass boost, if you need a little extra punch. Sony protects this amp with a 3-year warranty, and that says a lot.

Product Highlights:

  • 4-channel car amplifier
  • 70 watts RMS x 4 at 4 ohms (80 watts RMS x 4 at 2 ohms)
  • 160 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • separate variable high- and low-pass filters for front and rear channels (40-500 Hz, 12 dB per octave)
  • separate variable subsonic filters for front and rear channels (6-70 Hz, 12 dB/octave)
  • separate bass boosts for front and rear channels (0-10 dB at 40 Hz)
  • preamp and speaker-level inputs
  • cooling fan
  • fuse rating: 30A x 2
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 10-3/4"W x 2-1/8"H x 8"D
  • warranty: 3 years
  • 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.

Sony XM-GS400 Reviews

Average Customer Review:

5 Reviews

Stunning little amplifier

Written by: Jeff from Illinois on October 23, 2015

I read a review on this amp and figured I'd give it a shot. I'm very impressed with it. I'm not a fan of class D full range amps and needed something small but finding a small quality class AB amplifier is hard. This amp exceeded my expectations. Good job Sony. I also have the matching XM-GS100 monoblock driving two 8s. The GS100 is also an impressive little amp. The GS400 replaced a JL 300/4 (highly rated) and in my opinion the Sony has better imaging and a lower noise floor. This amp is dead silent when the signal is low. There's no idle hiss from this amp. That's a huge plus.

Pros: Low noise. Clear sound. Good power. Great image. No turn-on thump. Small footprint. Terminals all on the same side. Class AB. Reasonable price.

Cons: Terminals are the old-style barrier screws. I prefer the allen-head type terminals. They are better protected against shorts. Can run a little warm and care must be taken so the cooling fan has adequate airflow.

Cool Looking Amp

Written by: BambinozKustomz from California on May 8, 2015

Crutchfield Customer Review (What's this?)

I bought this amp because it had a fan at a great price but I wasn't getting the "Thump" I was looking for.After talking to one of Crutchfield's super cool tech's I realized I was way under powering my subs.So I took his advice and purchased a Sound Ordnance M-2250....all I got to say is Wow!!Very satisfied customer!!

Pros: Nice looking amp.Well built.

Cons: Not enough power!

Great Amp

Written by: BillyK from Wilmington, DE on October 31, 2014

Crutchfield Customer Review (What's this?)

I bought this to use for two sets of speakers and both my subs, and it works amazing. Very easy set up, and very easy change settings.



easy install

Written by: Mark W from Wichita, KS on September 30, 2014

Crutchfield Customer Review (What's this?)

easy to install. I have not finished installing speakers yet, so I have not adjusted levels. looks good, sounds good, great price for an amp with a fan

Pros: small amp for a tight install.

Cons: none

Works great for money

Written by: Mike from Tampa, fl on July 15, 2013

Crutchfield Customer Review (What's this?)

very pleased, didn't break the bank



Hands-on research

What's in the box?

Download owner's manual

  • Four channel amplifier
  • 4" Speaker level input harness
  • Two 30 amp ATO fuses (installed)
  • Four 1/2" Self-tapping screws
  • Operating instructions (English/ French/ Spanish)
  • Warranty information

Product Research


Overview: The XM-GS400 is is a four channel amplifier with independent controls for the front and rear sections. Both the front and rear sections are bridgeable, so the amp can be used in 4-channel, 3-channel, or 2-channel mode.

Protection Circuitry: The amp has three protection circuits:

  • Thermal: turns the amp off when the operating temperature is too high
  • Short circuit: turns the amp off when the speaker outputs are short-circuited
  • DC Offset: turns the amp off when it generates direct current

Crossover: The front and rear sections of the amp have independent crossover controls:

  • Mode: 3-position switch; Low Pass, Off (crossover is bypassed), High Pass
  • Frequency: 50-300 Hz; continuously variable

Subsonic Filter: The front and rear sections of the amp also have independent subsonic filter controls. The cutoff frequency is continuously variable from 6 Hz to 70 Hz.

Bass Boost: For added low frequency output, the amplifier has bass boost circuits centered at 40 Hz, variable from 0 to +10 dB. There are separate bass boost controls for the front and rear amplifier sections.

Power/Ground Terminals: The power and ground screw terminals are 0.55" wide.

Remote Terminal: The remote turn on screw terminal is 0.35" wide.

Speaker Outputs: Each speaker output screw terminal is 0.37" wide.

Speaker-level Input Harness: An 8-pin speaker level input harness is included, allowing you to easily connect the amplifier to a factory radio or a receiver without preamp outputs.

Auto Turn-on: When using the speaker level inputs, the amp will automatically turn on when it senses an input signal.

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.

Product reviews from the Crutchfield Labs

Sony's efficient GS car amplifiers give you clean, effective power to make your car audio system sing. There are two GS models: a 4-channel, and a mono subwoofer amp. Both feature RCA and...

Small but substantial

Written by Buck Pomerantz, Staff Writer - Creative, on 8/17/2012 5:07:00 PM

When I took it out of the box, the first thing that struck me was the heft. This amp's pretty heavy for something with a footprint smaller than a piece of letter-size paper. Over half its chassis is heavy heatsink. All the connections are on one side, and they appear to be gold-plated. The adjustment controls are under a removable cover, held in place with Phillips-head screws.

The instructions are on a large fold-out sheet of paper. They can be hard to follow if you don't read them carefully. Case in point: I would have never known there was a cooling fan aboard, if I hadn't read about not blocking the vent, which is on the top cover.

What are the Labs?

Customer Q&A

1 question already asked

The manual shows peak power as 350 watts x 2 (at 4 Ohms). [ Jeff  Feb 17, 2014 ]  Staff