Build your car audio system on a firm foundation of power. Kenwood amplifiers established their reputation with their rugged, no-nonsense reliability and superior sound quality. Heavy-duty internal components provide an abundant source of clean, crisp sound at a great price.

Your subwoofer needs a steady dose of power to drive it — the KAC-6401D mono amp delivers up to 300 watts RMS. A built-in low-pass filter adjusts amplifier output so you'll get the best sound possible from your subwoofer/box combo. Efficient MOSFET power supplies keep the juice flowing steadily, while the aluminum heatsink lets the amp stay cool, even when you're pushing it hard. Convenient speaker-level inputs let you hook a KAC-6104D up to your factory stereo.

Product Highlights:

  • mono subwoofer amplifier
  • 200 watts RMS x 1 at 4 ohms (300 watts x 1 at 2 ohms)
  • CEA-2006 compliant
  • variable low-pass filter (50-200 Hz, 12 dB per octave)
  • Class D design
  • preamp- and speaker-level inputs
  • level inputs
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 7-7/8"W x 2-3/8"H x 9-1/16"D
  • warranty: 90 days
  • Our 60-day money-back guarantee

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.

Kenwood KAC-6104D Reviews

Average Customer Review:

4 reviews
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Pleased so far....

Written By Lando, Athens, GA on Tuesday, February 15, 2011

Crutchfield Customer Review (What's this?)

I'm not sure if I got the last one, but I'm glad I did before they were no longer available. I
had it installed by one of the "big box retailers" and they did a pretty good job. It
improved the sound of the subwoofer in my BMW Z3 roadster giving it a nice clean, crisp
bass response without being booming, and coupled with my aftermarket Alpine receiver
I can control the sub level from inside the vehicle. I can't wait for the top down motoring
weather so I can let this much improved rich sounds out the cabin of my car.

Kenwood KAC-6104D

Written By Andrew, Des Moines, IA on Thursday, January 27, 2011

Crutchfield Customer Review (What's this?)

I love mine. I've had it for a year or so with no problems, and the price is right.

Good Amp, Great Support

Written By Glenn, Phoenix, AZ on Sunday, March 21, 2010

Crutchfield Customer Review (What's this?)

I have a Lexus GS 430 that has a factory sub in the rear deck. The factory sub blew out and everyone told me I needed to buy a "free air" sub or it will sound terrible. The second problem I encountered is all the manufacturers stopped making free air subs. I did not want a box taking up trunk space. The adviser at Crutchfield evaluated my situation and current factory system and recommended a 10" Polke Audio sub along with this Kenwood amp. I received my products and began the install process. I found that Lexus is not easy to install a rear sub in I called the Crutchfied support line a couple of times during my install. They were very helpful and kept me on track. I used the speaker level inputs into the Kenwood amp that use to run to my old factory sub. The sound and base is fantastic!

Good amp

Written By Zam09, Colorado on Wednesday, June 17, 2009

i bought this amp because it would save me 90 dollars to get this amp with
the speaker level inputs. It has plenty of power to drive an alpine type e
sub. Mine is hooked up to the factory stereo via the speaker level inputs.
my car gets loud and sounds great. My only complaint is that the sub will
get loud all the sudden but if you turn it down it then fixes itself.

Hands-on research

What's in the box?

Download owner's manual

  • Refurbished mono amplifier
  • One 30-amp fuse (installed)
  • Speaker-level input harness
  • 4 Self-tapping screws
  • Rubber terminal cover
  • Instruction Manual (English/ French/ Spanish)
  • Warranty Card

Product Research

Inputs and Outputs


CEA-2006 Compliant: CEA-2006 is a new system of testing and measurement methods for mobile audio amplifiers. This voluntary standard advocates a uniform method for determining an amplifier's RMS power output and signal-to-noise ratio. The criteria for measuring power uses a DC input voltage of 14.4 volts and the RMS power output is measured into a 4-ohm load, with 1% or less Total Harmonic Distortion (THD) plus noise, and at a frequency range of 20 Hz to 200 Hz when applicable. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. CEA-2006 allows consumers to compare car amplifiers and receivers on an equal basis. The Kenwood KAC-6104D under CEA-2006 regulations is rated at 200 Watts RMS x 1 channel with a 75 dBA signal to noise ratio.

Mono-Power Amp Design: The Kenwood KAC-6104D is designed with specific features to power your subwoofers with a frequency range between 20-200 Hz. This amplifier is not designed to power a full-range speaker.

2-Ohm Stable: The Kenwood mono-amplifier is capable of handling load impedances down to 2-ohms. The amplifier is rated at 300 Watts RMS x 1 channel in 2 ohms at 100Hz with 1.0% THD.

Class D Amplifier Design: The KAC-6104D is a Class D mono amplifier, which uses digital switching to amplify audio signals. This design results in high efficiency and less heat.

MOS-FET Switching Power Supply: The amplifier utilizes a MOS-FET switching power supply providing thermal stability and efficient switching speeds guaranteeing performance and dependability.

Parallel Connection: The amplifier is equipped with two pair of speaker terminals for an easy parallel subwoofer connection.

Low-Pass Filter: The KAC-6104D has a built-in 12dB/octave low-pass filter that is continuously variable from 50Hz to 200Hz.

Bass Expander: Turn on the Bass Expander for a more dynamic bass output at higher volume.

Line Level Inputs: The RCA type line-level inputs have a gain (Input Sensitivity) control adjustable from 200mV to 5.0 Volts.

Speaker Level Input: The KAC-6104D comes with a speaker level input harness. This feature makes it easier to add an amplifier to a factory radio or to a receiver with no preamp outputs.

Power Indicator: When the amplifier is turned on, the power indicator lights up. This indicator turns off with the amplifier and will turn off if the amplifier goes into protect mode.

Protection circuitry: The amplifier features protection circuits that will turn the amp off in case of the following events to protect the amplifier and your speakers:

  • Speaker wire short-circuits
  • Speaker output contacts ground
  • Unit malfunctions and DC is sent to speaker output
  • Internal temperature is too high
  • Loss of ground of head unit or amp


Left Side of the Amplifier: All of the amplifier's controls are found on the left side.

  • Bass Expander: on/off
  • Low Pass Frequency: 50-200 Hz
  • Input Sensitivity: 200mV-5V

Inputs and Outputs

Left Side of the Amplifier:

  • Line In: one pair of RCA inputs
  • Speaker-level Input: multi-pin input for use with the included speaker level input harness

Right Side of the Amplifier:

  • Fuse: One 30 amp ATO fuse
  • Power: screw terminal (0.34" wide)
  • Ground: screw terminal (0.34" wide)
  • Remote Turn-on: screw terminal (0.34" wide)
  • Speaker Outputs: two pair of terminals (0.34" wide), the two outputs are internally wired in parallel

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 verify what’s in the box, 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.