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Skar Audio

Skar Audio SK-M4004D Compact Full-Range Class D 4 Channel Car Amplifier, 400W

  • Based on 471 reviews
Condition: Used - Acceptable
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Availability: In Stock.
Fulfilled by SKAR AUDIO
Arrives Tuesday, Sep 1
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Size: 400 Watt RMS Class D Four Channel


Features

  • Ultra Compact MOSFET Full-Range 4-Channel Class D Car Amplifier
  • RMS Power @ 2 Ohms: 140 Watts x 4 Channels (14.4v)
  • RMS Power @ 4 Ohms: 100 Watts x 4 Channels (14.4v)
  • Crossover Controls: HPF / Full-Range / LPF | Frequency Response: 10Hz - 40kHz
  • Hi-Level Input Connections: Yes | 8 Gauge Power and Ground Input Terminals

Description

The Skar Audio SK-M4004D is an ultra compact, "mini", Class D full-range, four channel car speaker amplifier. The SK-M4004D was engineered to be compact, but provide the power and reliability expected out of larger amplifiers. Featuring a high speed MOSFET power supply, and an efficient Class D design, this amplifier is powerful, reliable, and extremely versatile. The SK-M4004D makes for a great amplifier in applications where space is limited but power cannot be sacrificed. In addition, this four channel amplifier features high level input connections for those installations that lack an RCA connection. In addition to the high level inputs, this amplifier also utilizes an adapter harness for the speaker outputs allowing for an easier and cleaner installation. Further adding to the feature rich list of this amplifier are its high pass / full-range / and low pass user controls, as well as having 4-Way Protection Circuitry Built-in (Thermal, Voltage, Speaker, DC). Utilizes 8 Gauge Power and Ground Input Terminals. Amplifier's dimensions: 7.9in x 4.6in x 1.7in (L x W x H). Frequency Response: 10Hz - 40kHz.

Item dimensions L x W x H: 7.9 x 4.64 x 1.65 inches


Voltage: 14.4 volts


Manufacturer: Skar Audio


Maximum Supply Voltage: 14.4 volts


Minimum Supply Voltage: 14 volts_of_direct_current


Voltage: 14.4 volts


Maximum Supply Voltage: 14.4 volts


Minimum Supply Voltage: 14 volts_of_direct_current


Mounting Type: Surface Mount


Number of Channels: 4


Output Power: 400 watts


Maximum Output Power: 400 watts


Item Dimensions: 7.9 x 4.64 x 1.65 inches


Material Type: Mosfet


Manufacturer: Skar Audio


Model: SK-M4004D


Brand Name: Skar Audio


Warranty Description: 2 year limited warranty


Unit Count: 1 Count


Global Trade Identification Number: 65


UPC: 739189979165


Included Components: Skar Audio SK-M4004D Compact Full-Range Class D 4 Channel Amplifier


Item Type Name: Car Amplifier


Item Weight: 3.7 pounds


Part Number: SK-M4004D


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Sep 1

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Powerful, Clean, and Compact 🔥
Size: 400 Watt RMS Class D Four Channel
This Skar Audio SK-M4004D amp is a beast in a small package — delivers crisp, distortion-free sound and plenty of power for all four channels. It runs cool, fits anywhere, and really wakes up your speakers. Perfect mix of size, strength, and quality. 💪
Reviewed in the United States on October 14, 2025 by David Houck
    • Don't need subs with one of these and a good set of speakers.
Size: 400 Watt RMS Class D Four Channel
This amp gave my system just what it needed. I was running brand new cerwin vega speakers directly off my new Android deck via wiring harness and stock speaker wires and it just sounded flat and week. I got this amp and some 16ga speaker wire and rewired the whole car and now it sounds so rich, warm, and powerful. With the eq set to hip hop and the bass boat turned on, you probably don't need a subwoofer. I have a sub in my car and it was overpowering my speakers. This amp does a great job compensating for the bass. It made all the difference in creating a rich full sound and making one of the best sounding car stereos I've ever heard. 10/10 would recommend. ... show more
Reviewed in the United States on April 16, 2021 by Quenten
    • Good stuff.
Size: 400 Watt RMS Class D Four Channel
Been using it for a couple years now.No issues with it.Better and cheaper than the amps I built system with way baack in the day.
Reviewed in the United States on June 3, 2026 by Amazon Customer
    • It's the best you can get at this price.
Size: 400 Watt RMS Class D Four Channel
The amplifier is in itself built well and performs as you can expect a budget friendly amp will. As per sound quality I installed this on my truck and it is quite comparable to the 600$ old kenwood that came out of it. It however does have some things to note that are important at this price point, the warranty is voided as soon as you install this thing, the internal components however good are still basic in nature, the installation process is slightly tedious with the output side clip but is expected, and the amp does get quite warm. Because the amp is basic in nature it lacks (at least in my experience) a line filter so that power from your alternator does not affect sound quality. You can simply buy a noise suppressor for the power feed to solve this issue. I did experience the fan never turning off and this was a problem as it does make an audible noise while on. I after already installing the unit and figuring this out, decided to break down the amp and disconnect the fan altogether. There is a simple clip you undo that is delicate but doable. THIS WILL VOID A WARRANTY. But it did solve my problem and after dynoing my 4 door speakers at full throttle for 20 minutes my amp did not get hot just the warmer side of things. After all the little fan didn't do much. I only did this because my amp is mounted by floating brackets under my passenger seat; if this was in a glove box or the trunk of a car there would be no problem. Other than the the sound quality is clean and powerful, the unit is built well and on the good side of heavy (not feeling cheap), and I can expect it to last. Update* the amplifier died after a few months of running it hard. However if you run it well within its ratings I believe it should hold up well ... show more
Reviewed in the United States on May 22, 2022 by Jerry Westheimer
    • Bought Mar 2018. Broke September 2018.
Size: 400 Watt RMS Class D Four Channel
Review Image by John
Review Image by John
Review Image by John
*EDIT 9/19/2018* --I have received a response from Skar support. Their answer was as follows: ""Thank you for reaching out to us concerning your SK-M4004D amplifier. Sadly, once you opened the unit to preform an inspection on it; you voided your warranty. However, not all hope is lost. Your unit can still be repaired at our authorized repair center."" --Out of the 6 screws on the back, none were marked as "warranty void if removed". Nothing I have ever worked on in the past (including laptops and other HIGHLY technical electronics) have ever voided the warranty just because the back plate is removed! Never in my life have I ever heard of such a thing. If Because I had volunteered the information about what I had done to investigate the issue, they are now stating that the warranty was voided. I didn't even touch the circuit board! Nowhere on the product OR on their website warranty procedures does it state that removing 6 screws to investigate behind the backplate will void a warranty. NO WHERE! Yet they want to tell me that I voided the warranty because of these screws that could have been rattled out (not even pasted/glued in, or even some weird hex head type!). --Thanks. Skar. You lost ALL business from myself and from my friends/family! --If I could give Skar a 0-star , I would, but suffice to say: STAY AWAY AND BUY SOMETHING ELSE/BETTER!!!!! THEY WILL NOT SUPPORT THEIR CLAIMS FOR WARRANTY!!! **original posting** --I'm not sure on if I would ever recommend this product. One coil is completely broken out while another coil is hanging on by one end. --I took off the backplate when I heard the rattling around inside in order to investigate what was going wrong. --Notice my internal photos and compare them to the stock photos on Amazon listing: In my photo, the amount of glue that holds the coils isn't anywhere near as it is in the stock Amazon photo. Odd, right? Skimping on glue to save a buck. Bad Skar, no cookie. --I have contact Skar to find out about a repair/replace, but I am not expecting much from the company. Supposedly, Skar covers their products for 2 years, but I have a feeling that they are going to pull the "Amazon isn't a branded/licensed/reputable/overpriced dealer, so we won't cover!" --Funny thing is, no other hardware that I have on my vehicle has ever fallen apart like this, especially in such a short timeframe. --Do I expect them to respond? No. --Do I expect a response that actually is beneficial to me? No. --Why do I not expect these things? Because I have had too many bad experiences with manufacturers in the past and I'm still a bit jaded over them. --Would it be nice if something were to come about that would be beneficial to the customer? Heck yeah! But not expecting it. --I'll keep this updated if Skar can come through with a decent reply (if any at all). ... show more
Reviewed in the United States on September 18, 2018 by John
    • small but powerful
Size: 400 Watt RMS Class D Four Channel
I bought this for a stereo retrofit project on my 1987 BMW 635Csi. Its a good little amp; puts out a ton of power in a small package. No problems installing it, pretty basic. Minor issue : fan mounted on the bottom so you need to stand it off the mounting surface just a bit. Some have said it gets hot but mine does not at all.... as long as you let some air in/out of the bottom surface vents it's entirely cool. Would definitely purchase it again. ... show more
Reviewed in the United States on February 4, 2024 by Bkewc
    • No wine and no popping when turning on and off
Size: 400 Watt RMS Class D Four Channel
Very impressed with the clarity and sound from a no name amplifier we’ll see how it holds up
Reviewed in the United States on April 8, 2026 by Darrkon
    • Good sound. Small size. Runs hot
Size: 400 Watt RMS Class D Four Channel
Review Image by BigStuwop
I’m using this to run Skar TX components and coaxials and I love the sound it produces. The amp is gain matched down to 50 watts per channel and still gets loud and clear. The amp does run very warm though, even in cold weather. The small profile makes it fit easily into any system where space is at a premium. ... show more
Reviewed in the United States on January 8, 2023 by BigStuwop

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