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Soundstream USB.8A

150 Watt Powered & Preloaded Under Seat Loaded Enclosure with 8" Subwoofer

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List price $299.95

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Soundstream USB.8A

150 Watt Powered & Preloaded Under Seat Loaded Enclosure with 8" Subwoofer


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100% Copper, 2-Channel True Spec 8 Gauge Amplifier Installation Kit



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15% Off a Sound Dampening Kit with Your Subwoofer Purchase!

Add an NVX SDTK20 Sound Dampening Trunk Kit to your Subwoofer purchase and save 15%. Simply click the "Add Both to Cart" button. This offer cannot be combined with any other coupons or offers.




Soundstream USB.8A



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Special Price $45.89 ($53.99 if purchased separately)


• Eliminates Road Noise
• Quiets Vibrations
• Stops Rattles • Increases SPL
• Reduces Heat
• Simple To Install
• Easy To Form Aluminum
• Four Step Peel and Stick Installation
• Five 18" x 32" Pieces

(Offer 1 of 1)

Combined Total Price


You Save $8.10

Soundstream Audio Store

General Features:

  • Under Seat Loaded Enclosure
    • 150W amplifier built-in
    • Preloaded 8" Subwoofer Driver
  • Wired remote bass level control included
  • LED power and protect indicators
  • Speaker-level (high-level) inputs
  • Nickel-plated power, ground and RCA terminals
  • Heavy duty aluminum alloy heat-sink for extreme heat dissipation
  • Input sensitivity: 200mV - 3V
  • Frequency Response: 30 - 150 Hz
  • Total Harmonic Distortion (THD): 0.5%
  • Signal to Noise Ration: 95dB
  • Selectable phase shift: 0 - 180°
  • Variable low-pass filter: 50 - 150 Hz, 24 dB/octave
  • Variable Bass Boost: 0 to +12 dB bass boost at 45 Hz
  • Fuse Rating: 15A x 2
  • Color: Black
  • Mounting screws included
  • Dimensions: 3"W x 9.5"D x 14.5"H
  • 8 gauge power and ground wiring is recommended for installation. Contact us for information regarding a discount on select amplifier kits from our website when purchased together with this amplifier
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Amplifier Specifications

Total RMS Power Output
Total RMS power is measured by multiplying RMS power per channel by the number of channels, and is calculated at the lowest level of operating impedance.

RMS power is the amount of continuous power, measured in watts, that an amplifier produces is called RMS power. The higher the RMS figure, the louder and cleaner your music sounds.

The RMS output figure is much more accurate than the peak rating when comparing products.

150 watts
Maximum Input Gauge Size
This is the largest gauge wire that will fit into the power and ground terminals of this device. The lower the gauge number, the thicker the wire is. For example, a 4 gauge wire is thicker than an 8 gauge wire and thus has higher current carrying capacity. Always do your best to get this size wire to reduce the risk of damage to your components.
THD at Rated RMS Power
The amount of change in harmonic content of the signal as it is amplified. A lower figure indicates less change and a more accurate amp. THD below 0.10% is inaudible.
Speaker Level Inputs
Speaker level inputs are commonly referred to as high-level inputs and vice versa. This input type allows you to get your audio signal directly from the speaker wire in your vehicle, instead of using RCA cables. The advantage of this is factory integration, as most stock radios do not have RCA outputs to run amplifiers.
Yes - with included adapter
Preamp Outputs
Many amplifiers are equipped with RCA preamp outputs which pass the original music signal from the source to additional amplifiers. This is known as daisy chaining because the source connects to the first amp, and the first amp connects to the second amp, etc. The advantage to daisy chaining is you only need one 2-channel RCA cable to transfer the signal from the head-unit to the amplifier, and then one additional cable for each amp being daisy chained.
Built-in Crossover

A crossover is a type of filtering system that permits only certain frequencies to play. A Low-Pass (LP) crossover allows only frequencies below its setting to get through which is good in the case of some subwoofers. A High-Pass(HP) filter allows frequencies above its setting to pass through, this is normally used on speakers.

When a crossover is set to FULL it means no filtering is added and the full frequency spectrum is allowed through the amplifier. Filtering is important because feeding a speaker frequencies it cannot reproduce effectively creates distortion.

Low-Pass (LP)
Low-Pass Crossover Frequency
The low-pass crossover frequency is typically used for subwoofers. It can be a fixed crossover point or a variable crossover range. A variable low-pass crossover allows you to select a specific crossover point which allows frequencies below the set crossover point to pass, while making frequencies above the set point gently or harshly roll-off, depending on the steepness of the slope.

The steepness of the roll-off slope is measured in dB/octave and refers to the rate of attenuation (lowering of volume) outside their pass bands.

50 - 150 Hz
Signal-to-Noise Ratio
This spec compares the strength of the signal to the level of background noise. A higher value indicates less background noise.
95 dB
Bass Boost
The objective of the bass boost is to get more kick out of your subwoofer. It is a circuit that emphasizes the lower frequencies at a given point. The bass boost should always be set first before setting the gain. This feature is known for destroying subwoofers and is commonly used incorrectly, so be cautious.
0 - 12 dB
Bass/Gain Remote
If the amp comes with a bass/gain remote you will be able to control the level of your bass from your dashboard. Typically bass remotes also include a 16-20 ft. wire for installation.
Fuse Rating
The amperage and the number of fuse(s) an amp requires.
15A x 2 

Subwoofer Specifications

Subwoofer Size
Refers to the diameter of the subwoofer, measured in inches.
Woofer Composition
Lightweight woofer cone materials are essential for efficient operation. Poly cones produce exceptional sound and are sturdy against various changes in temperature. Paper cones are very efficient, and when treated for moisture resistance, will perform at a high level. Poly refers to polypropylene, which is thermoplastic or fibers that are polymers of propylene. IMPP refers to injection molded polypropylene, a commonly used process and material in speakers.

Enclosure Specifications

Box Type
Represents the style of the enclosure. Be sure to purchase the appropriate enclosure type and internal volume that will be compatible with your subwoofer's recommendation.

Sealed - Sealed boxes are those that have no holes or vents in it. The only hole in a sealed box is where the subwoofer is installed. Smaller sealed boxes require more power than a larger sealed box. They provide a tight, accurate bass, while the larger sealed enclosures provide a "boomier" and louder bass.

Ported / Vented - Ported/Vented Enclosures provide an even boomier, louder bass, but less accurate then a small, sealed box. Ported enclosures typically require more airspace per sub and also less power output from an amplifier to perform correctly.

Bandpass - Bandpass enclosures make subwoofers perform efficiently, but loose. The bass is not as "boomy" as a ported enclosure nor as punchy as a sealed enclosure. Bandpass enclosures work well with lower to mid-level subwoofers.
Number of Subs/Speakers
This value represents the number of speakers or subwoofers that the enclosure accommodates.
Box Style/Shape
The box style or shape refers to the actual shape of the box. Square and rectangular boxes are straight-edged boxes on all sides, whereas hatchback and truck style enclosures feature an angled front or back design that allows for installation in places short on depth such as single cab pickup trucks. You can also use such enclosures in hatchback cars or other vehicles where space is a premium. Tube and cylinder shaped boxes were made popular by Bazooka and are a great option for those looking for a nice amount of bass without sacrificing lots of space. They may even fit in locations that slim truck boxes cannot fit in. If the enclosure is vehicle specific, we encourage you to read the product description to find out which vehicles the enclosure is made for.
The height of the item, measured from top to bottom, in inches.
The width of the item from left to right (side-to-side) measured in inches.
The front-to-rear depth of the item, in inches. If the item is angled or slanted, this value is the bottom measurement.
Number of Terminals
The number of terminals the enclosure has. Each terminal represents 1 positive and 1 negative.
Box Exterior Color
The color of the enclosure's exterior/outer finish.

Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
4 Star
3 Star
2 Star
1 Star

Average Attribution Rating


Cincinnati, OH

Verified Purchase
I wouldn't buy it

October 2, 2015

I bought this to mount in a 2 door coupe with limited space and it really left me wanting more. I went into it being a Soundstream fan and open mind. It does seem to run very hot and it kept cutting in and out which I found was a problem other people have had. The sound quality was ok but not to my satisfaction. It's ok for what it is but its a small enclosure so it can only do so much. I returned it and bought a separate sub and amp combo and I am much happier now. It's well built but don't expect a lot. You are better off buy a seperate amp and sub combo if you have the room.

4 of 5 found this helpful

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Verified Purchase

April 1, 2016

First time for me installing a powered sub or even a sub too. I ran the power wire from my battery + through the left fender on my 04 Dodge Intrepid and thankfully there was already a dummy hole in the right spot on the car body into the cabin with a ruber grommet for insulation. The important thing for these is to not run the powered wire next to other wiring to avoid distortion. I really like the added ooomph this gives to my 2 rear MB Quarts and 2 front NVX's. Only drawback is it really does not fit cleanly under the passenger front seat. Has to stick out a little into the rear footwell. The remote if nice and when you turn down the sub volume you can really notice the difference without it.

1 of 1 found this helpful

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Detroit, mi.

A must buy!

January 11, 2016

This system has good sound and easy to install for a DIY'er! It also is a great value!!!

1 of 1 found this helpful

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Raleigh, NC

sounds great!

October 26, 2016

Exactly what i was looking for to fit in my wrangler, under the rear seat. Sounds way better than other compact systems I've seen in my friends vehicles.

0 of 0 found this helpful

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Detroit, mi.

A must buy!

January 10, 2016

This system has good sound and easy to install for a DIY'er! It also is a great value!!!

0 of 0 found this helpful

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Accessory Tools and Products

Accessories added


100% Copper, 2-Channel True Spec 8 Gauge Amplifier Installation Kit

Your Price $49.99

Belva BAK82BL

Complete 8 Gauge Amplifier Wiring Kit with 2-Channel RCA Cable (CCA Wiring)

Your Price $12.99


Trunk Kit - 20 Square Feet of Sound Dampening Material (Five 18" x 32" Pieces)

Your Price $53.99

Dynamat Xtreme 20' Trunk Kit 19405

20 ft. Trunk Kit with (5) Dynamat Extreme 18" x 32" Pieces

Your Price $97.97

Boom Mat Damping Material (050210)

20.8 sq.ft Damping Material - (10 pk - 12-1/2" x 24" x 2mm )

Your Price $109.99

Browse 3 questions and 4 answers
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Why did you choose this?
Sonic Electronix Store
I needed to save space, the price was right, and it had good specs.
terrence m on Aug 3, 2016
Is warranty 3 yrs + 1 yr factory = 4 yrs?

What gauge wire is needed for power/ground connection?

A shopper on Sep 10, 2014
Best Answer: Hello,

No. The extended warranty is a TOTAL of 3yrs. [i.e. 1-year Manufacturer's Warranty + 2-Year SquareTrade Warranty] .
In regards to the Power/Ground; The USB.8A calls for 8 Gauge Power/Ground, like that found in the NVX XKIT82.

Reply · Report · Customer SStaff on Sep 10, 2014
· Add Answer · I Have This Question Too (0)
can two of these units be used together on the same stereo system?
chris f on May 13, 2016
· Add Answer · I Have This Question Too (0)

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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Soundstream USB.8A