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.

Our take on the Sony XM-GS400

by Buck Pomerantz

Brings you the music

You'll get 70 watts RMS to each of your front and rear speakers with Sony's XM-GS100 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-GS100 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

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.

See more info on this item

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
4-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
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Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and specs chart | What’s in the box? | In-depth notes

Features and Specs

Performance
RMS Power Output (Watts x Channels) Loading...	70 x 4
Peak Power Output (Watts x Channels) Loading...	175 x 4
Power at 2 Ohms (Watts x Channels) Loading...	80 x 4
Bridged Power (Watts x Channels) Loading...	160 x 2
Minimum Impedance Bridged Loading...	4
Minimum Impedance Unbridged Loading...	2
Best Frequency Response Loading...	10-100k Hz
THD at Rated RMS Power Loading...	1%
Signal to Noise Ratio Loading...	93 dB
Input Voltage Loading...	14.4v
Features
Amplifier Class Loading...	Not Given
Low-Pass Crossover Frequency Loading...	50-300 Hz
Low-Pass Slope (dB/octave) Loading...	12 dB/octave
High-Pass Crossover Frequency Loading...	50-300 Hz
High-Pass Slope (dB/octave) Loading...	12 dB/octave
Bass Boost Loading...	0-10 dB
Bass Boost Frequency Loading...	40 Hz
Fan Cooled Loading...	Yes
Fuse Rating Loading...	60
Speaker Level Inputs Loading...	Harness
Preamp Outputs Loading...	No
Width (inches) Loading...	10-3/4
Height (inches) Loading...	2-1/8
Depth (inches) Loading...	8
Parts Warranty Loading...	3 Years
Labor Warranty Loading...	3 Years

Product 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

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.

Features

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.

Product reviews from the Crutchfield Labs (what are the Labs?)

Video: Sony GS Car Amplifiers

Video Guest

10/5/2012

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...

Quick impressions from the Lab

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.

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