About the Sony XMS400D
Meet Buck Pomerantz
I belong to a culture of fine sights and sounds, and I like spreading the word.
I've been tinkering with electronics ever since I was a kid - starting with taking apart and putting back together televisions and radios. I always got them back together again and working. I took courses in radio and electronics as a teenager, and became a ham radio operator. I worked in my high school's stage crew, running sound, lights, and a movie projector. After college, I joined a rock 'n roll band as the soundman and learned how to lug around and operate the gear that helps make music sound good and loud.
Working in a music store in Austin, Texas, I spent a few years manufacturing, installing, repairing, and operating sound systems. Our customers were recording studios, nightclubs, and touring bands. Eventually I moved back to Charlottesville, Virginia and opened a small demo recording studio. In 2006, I finally came to my senses and got this job at Crutchfield. They actually pay me to ramble on, rant, and explain the things I love about music, electronics, and getting good sound.
Given my background, they put me to work writing about some of the most complex electronic products Crutchfield sells: car amplifiers, digital signal processors, wiring, professional sound mixers, and PA systems.
More about Buck
- Started at Crutchfield in 2006
- Completed our thorough in-house Advisor training, learning about the ins and outs of our various products
- Stays up-to-date by attending vendor training sessions for new products
- Earned MECP (Mobile Electronics Certified Professional) certification
- Designed and organized Crutchfield's subwoofer wiring diagrams
- Authored dozens of Crutchfield articles and hundreds of product presentations, primarily focused on car audio amplifiers and pro audio gear
- Answers the many customer questions posted in the comments on his articles
- Semi-retired soundman with decades of experience making other people sound good
- From 1999 to 2018, also worked as a sidelines video camera grip for University of Virginia football and basketball games
More from Buck Pomerantz
Seriously small amp
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.
- 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
See the difference between "Open Box" and "Scratch & Dent" Outlet items
Small in size but powerful in output. It fit extremely well in the 4 din enclosure and makes my Sony AX sound so good. I would highly recommend this Sony amp. It is smaller than an old school blackboard eraser.
Brian from Flowood, MS
I have read reviews that some of these type units get very hot. Is it safe to tuck behind the radio in a small spot touching wires and such?
I don't know about behind the radio but I do have mine behind the glove box and have not had any problems. Make sure you tape up the wires and you should be fine.
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More details on the Sony XMS400D
Features & specs
|RMS Power Output (Watts x Channels)||
45 x 4 |
|Peak Power Output (Watts x Channels)||100 x 4|
|Power at 2 Ohms (Watts x Channels)||N/A|
|Bridged Power (Watts x Channels)||N/A|
|Minimum Impedance Bridged||N/A|
|Minimum Impedance Unbridged||4|
|Best Frequency Response||20-20k Hz|
|THD at Rated RMS Power||1%|
|Signal to Noise Ratio||83 dB|
|Low-Pass Crossover Frequency||120 Hz|
|Low-Pass Slope (dB/octave)||12 dB/octave|
|High-Pass Crossover Frequency||120 Hz|
|High-Pass Slope (dB/octave)||12 dB/octave|
|Bass Boost Frequency||N/A|
|Speaker Level Inputs||Harness|
|Parts Warranty||1 Year|
|Labor Warranty||1 Year|
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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