Soundstream Stealth ST4.1000D

Compact 4-channel car amplifier — 90 watts RMS x 4

  • Soundstream Stealth ST4.1000D


  • Soundstream Stealth ST4.1000D

  • Soundstream Stealth ST4.1000D

  • Soundstream Stealth ST4.1000D

  • Soundstream Stealth ST4.1000D

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Our take on the Soundstream Stealth ST4.1000D

by Bob Bihlmayer

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.

Big sound, small package

If you're in need of an amplifier that takes up liitle space but delivers a big sound, Soundstream's Stealth amplifiers can fill the bill. At about 3" deep by 7-1/2" wide, the ST4.1000D 4-channel amp will fit just about anywhere, delivering 90 watts per channel to your front and rear speakers, or up to 250 watts per channel in 2-channel mode to your subs. That's a lot of power in a tiny package.

You're in control

The ST4.1000D also features high- and low-level inputs for a variety of applications, and includes high- and low-pass filters to help you tailor your sound. And Soundstream built this amp for the long haul with its MOSFET power supply and military-spec circuit board, surrounded by an aluminum alloy heatsink and guarded by full short-circuit, thermal, and overload protection circuitry.

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  • 4-channel car amplifier
  • 90 watts RMS x 4 at 4 ohms (125 watts RMS x 4 at 2 ohms)
  • 250 watts x 2 bridged at 4 ohms
  • variable high- and low-pass filters (35-250 Hz, 12 dB/octave)
  • Class D amp technology
  • MOSFET power supply
  • preamp and speaker-level inputs
  • fuse rating: 30A x 1
  • 10-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • dimensions: 7-1/2"W x 1.5"H x 3-1/8"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) 90 x 4
Peak Power Output (Watts x Channels) 500 x 2
Power at 2 Ohms (Watts x Channels) 125 x 4
Bridged Power (Watts x Channels) 250 x 2
Minimum Impedance Bridged 4
Minimum Impedance Unbridged 2
Best Frequency Response 20-30000 Hz
THD at Rated RMS Power 0.05%
Signal to Noise Ratio 70 dB
Input Voltage 14.4v
Amplifier Class D
Low-Pass Crossover Frequency 35-250 Hz
Low-Pass Slope (dB/octave) 12 dB/oct
High-Pass Crossover Frequency 35-250 Hz
High-Pass Slope (dB/octave) 12 dB/oct
Bass Boost No
Bass Boost Frequency N/A
Fan Cooled No
Fuse Rating 30
Speaker Level Inputs Harness
Preamp Outputs No
Width (inches) 7-1/2
Height (inches) 1-1/2
Depth (inches) 3-1/8
Parts Warranty 1 Year
Labor Warranty 1 Year
Product Research
What's in the box?

Download owner's manual

  • 4-Channel Class D amplifier
  • One 30A ATM fuse (installed)
  • Two 8.25" Speaker-level input harnesses (with 5-pin Molex connector)
  • Two 6" Line-level input harnesses (Stereo female RCAs on one end and 5-pin Molex plug on other end)
  • 6" Speaker output harness (with 8-pin Molex connector)
  • 6" Power harness (with 6-pin Molex connector)
  • 4 Self-tapping screws (Length=5/8")
  • Owner's Manual
  • Power Harness Wiring Diagram

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.



Overview: The Soundstream Stealth-series amplifiers pack a powerful punch from a small chassis. This 4-channel, full-range Class D amplifier can drive two pairs of speakers, or two subwoofers, without taking up a lot of space.

Power Output: The ST4.1000D micro-mini amp delivers 90 watts x 4 channels at 4 ohms, and 125 watts x 4 at 2 ohms. Bridged output is 250 watts x 2 (4 ohms).

High/Low Level Input: The amp includes plug-in harnesses for both high-level and low-level inputs. Speaker wires from the source unit can be spliced onto the two supplied high-level input harnesses. If you're using the preamp outputs from the source unit, you can plug in your RCA cables into the two low-level input harnesses. Both harnesses have a 5-pin Molex connector that plugs into the amp's Hi/Lo Input.

Note: If you're using the high-level inputs, you do not need to run a remote turn-on lead. The amplifier will automatically turn on when it senses an input signal.

LEDs: The amp features two LEDs to indicate the status of the amplifier. The green LED will glow when the power to the amplifier is on. When the red LED glows, the amplifier's protection circuitry is engaged, shutting down the amp.

Protection Circuitry: The protection circuitry will shut down the amplifier for the following conditions:

  • Overheating: Thermal protection can be caused by too low of an impedance or inadequate air flow around the amplifier.
  • Over-/Under-Voltage: The amp will shut down if the voltage to the amp is not within 10 to 16.8 Volts DC range.
  • Short Circuit: When speaker wires become shorted to each other or to the vehicle chassis, the amplifier will shut down.


Gain: The ST4.1000D's rotary gain controls let you match the amp's input sensitivity to the output of the source unit. There are independent gain controls for the front and rear channels of the amp. The input sensitivity range of the amplifier is continuously variable between 0.5V and 12V. A small screwdriver (not included) is required to set the gain.

Crossovers: The amp features independent 12 dB/octave crossovers that can be set to High-pass (HPF), Full Range, or Low-pass (LPF). The cutoff frequencies can be independently set between 35Hz and 250Hz using the rotary controls.


Molex Connections: The Soundstream ST4.1000D uses compact Molex connectors which plug into the amplifier for the amp's input, speaker output, and power/ground/remote turn-on connections.

Power: The Power/Ground/Remote harness contains two 16-gauge red +12V power wires. These should both be spliced to your power wire (not included) which runs from the amp to your battery. You should use at least a 10-gauge power wire to the battery, with an in-line 30A fuse no more than 18" from the battery terminal.

Ground: Like the power wires, there are two 16-gauge black ground wires. Both should be spliced to a larger gauge ground wire (not included) and attached to a metal area close to the amplifier. The ground wire should be the same gauge as the power wire.

Note: There is also a dark blue "secondary ground" wire in the harness. Generally, it should be connected to the main ground wire. However, if engine noise appears in the system, the dark blue wire should be connected to the source unit's chassis ground.

Remote Turn-On: The orange wire in the harness is for the amplifier's remote turn-on circuit. This should be spliced to a remote wire (18-gauge typically) that runs to the source unit. This connection is not needed if you are connecting the amplifier to the source unit via a high-level input.

High-Level Input: If you're connecting the amplifier to a factory head unit, or a unit that does not have preamp outputs, you should use the amp's high-level input. Splice the source unit's speaker wires to the two High-Level Input harnesses and plug them into the amp's Molex connectors.

Low-Level Input: The amp's two Low-Level input harness each have two female RCA connectors that will accept the plugs of an RCA patch cable from the head unit. The other end plugs into the amp's Molex connector.

Speaker Outputs: The amp features a speaker output harness with connections for 8 speakers. Speaker wires should be spliced onto the speaker output harness.

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Soundstream Stealth ST4.1000D Reviews

Average Customer Review:

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2 out of 5

True RMS is much lower

Written By Anonymous, Charlotte, NC on Tuesday, August 26, 2014
Amp is very nice and compact but doesn't put out anywhere near advertised. I tested it with a handful of frequencies 60Hz-8000Hz running output to four 4 ohm speakers and got between 45 and 55 watts before amp clipping. I knew it wouldn't put out what it said but didn't think it would be off by half. It has a 30 amp fuse, which is low for specified power output.
Small, easy to install in tight spaces
Power output isn't as advertised Power and ground connections are small and difficult to hook up
4 out of 4 people found this helpful
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5 out of 5

ALittle Gem

Written By Soso, NJ, USA on Thursday, August 14, 2014
Crutchfield Customer Review (What's this?)
I'm giving this little gem 5 stars. I had a Alpine KTP445U. That amplifier was good but after installing the Soundstream, I am more than satisfied with this product.

I have MTX Thunder65 coaxial on all four of my doors. Those speakers are rated for 60watts RMS. I spoke to MTX support and asked if this amp, because its RMS rating is 90, would cause any damage to the speakers. He said as long as I adjust my gains to prevent clipping I wouldn't have a problem feeding the wattage the Soundstream would give out. I immediately noticed a more solid mid bass as well as cleaner vocals with this amplifier after raising the volume. I adjusted my gains using a SMD Distortion Detector playing track 4.

Wiring was simple as I already had the wiring in place from the previous amp - the Alpine KTP445U. I placed the Soundstream behind and to the side of my glove box compartment under the dashboard. It fit snugly on a surface area with room around for breathing.

I thought the Alpine was good but this Soundstream is a better choice. I like the ease of installation and its size. The size was the selling point as I didn't want to run wiring to the rear of my SUV. I used 10 gauge wiring for power and ground with a 30 amp fuse. I twisted the 2 power wires from the amp connectors together as well as the 2 ground wires, connected them to power and ground and off I went. This amp doesn't come with the orange wire shown in power connection picture
3 out of 3 people found this helpful
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5 out of 5

Great Amp For the Price

Written By SoundStream Owner, PHX on Tuesday, August 05, 2014
Crutchfield Customer Review (What's this?)
I bought this amp, because I didn't have room to install an older JL Audio amp in my truck. I have it connected to Focal speakers in the front, MB Quart in the back, and a JVC media only head unit. For the money, i think it sounds amazing. I'm very picky about sound quality and wasn't disappointed.
-Size -Power -Mounting options -Sound Quality Give this amp a shot...you'll be surprised!!
A little disappointed in: - Power/Ground/Remote connections, but given the size of the amp, its acceptable. - Speaker connections are tiny...but, again..given the size of the amp, i can overlook that.
7 out of 7 people found this helpful
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2 out of 5

Cheaper than I expected

Written By Radio-Upgrade, Round Rock, TX on Friday, June 27, 2014
Crutchfield Customer Review (What's this?)
When I unboxed the amp and looked at it, I was disappointed. I thought that the quality looked poor, and I decided not to install the unit.
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1 question already asked

Can it run 3 channel mode and do half what it says it can? I installed pro for 20yrs, have been out of it sense 03, I can not believe something smaller than .. .... can make that kind of power. [ Kraig  Jul 01, 2014 ]
1 answer
  • We have not received any answers from other customers on your question. I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They should be able to help answer your question. [ Krissy Staff  Jul 09, 2014 ]

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