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Kenwood makes tough, rugged amplifiers that bring you superior sound quality along with reliable performance. Add a Kenwood Sports Series amp to your system, and you'll hear all the tonal color, impact, and detail you've been missing, from the punch of the rhythm section to the shiver induced by your favorite singer's voice.

The KAC-2404S 4-channel amplifier delivers 40 watts RMS per channel to your full-range speaker system. This amp will bring new life to your factory speakers, but you'll really notice the difference when you pair this amp with new aftermarket speakers. Switch the amp over to 2-channel mode, and you can get great performance from a set of components or a couple of subs with 130 watts RMS per channel. This versatile amp features separate frequency filters for the front and rear channels, along with preamp and speaker-level inputs, so it'll fit in just about any system.

Product Highlights:

  • 4-channel car amplifier
  • 40 watts RMS x 4 at 4 ohms (60 watts x 4 at 2 ohms)
  • 130 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • switchable high-pass filter (80 Hz, 12 dB per octave) on front (A ch) channels
  • variable low-pass filter (50-200 Hz, 18 dB per octave) on rear (B ch) channels
  • MOSFET power supply
  • preamp and speaker-level inputs
  • requires 10-gauge power and ground leads — wiring and hardware not included with amplifier
  • fuse rating: 30A x 1
  • 13-13/16"W x 2-3/8"H x 8-1/2"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-2404S Reviews

Average Customer Review:

5 Reviews

Kenwood KAC-2404S

Written by: Powerhaulic from Adirondacks, NY on August 14, 2013

Crutchfield Customer Review (What's this?)

Works great, no pops on power up

Pros: All Good

Cons: none so far

Kenwood KAC-2404S

Written by: Anonymous from Greenville, SC on January 23, 2013

Crutchfield Customer Review (What's this?)

Works like I thought it would. Powers my four kenwood speakers perfectly, wasn't expensive compared to others, and gives the speakers I had also recently installed the power they needed.

Pros: inexpensive, so far reliable (only installed 1 month), aesthetically nice if mounted in a visible area, was able to fit it under a '97 cherokee rear seat! (Barely)

Cons: None so far

Great amp

Written by: Ken from Summerville on October 14, 2012

Crutchfield Customer Review (What's this?)

This is a great amp. Easy installation and easy to tweak for a great sound.



Kenwood Amp

Written by: Kenwood KAC-2404S from York,Pa on January 23, 2012

Crutchfield Customer Review (What's this?)

This did the trick kicking up my receiver and bass. Very pleased.



Good Solid Amp

Written by: Dave S from East Windsor, CT on May 18, 2011

Crutchfield Customer Review (What's this?)

Bought this amp for my wife's car. It sounds very good, giving the bass a solid
punch and overall sound quality is great. I find the physical size a little big
as compared to other 4x40 amps. The price here is higher than other places and
Crutchfield doesn't provide significant freebies for amps like they do with
speakers and receivers.



Hands-on research

What's in the box?

Download owner's manual

  • Refurbished 4-channel amplifier
  • 30 amp ATO fuse (installed)
  • 7" Speaker-level input harness
  • Four 5/8" Self-tapping screws
  • Instruction manual (English/ French/ Spanish)
  • Warranty information

Product Research

Warranty Note


CEA-2006 Compliant: CEA-2006 is a system of testing & 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 plus noise (THD+N), and over a frequency range (for full range amplifiers) of 20 Hz to 20,000 Hz. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. CEA-2006 standards allow consumers to compare car amplifiers and receivers under the same conditions (apples to apples). The Kenwood KAC-2404S under CEA-2006 regulations is rated at 40 watts RMS x 4 channels with an 80 dBA signal to noise ratio. The signal to noise ratio at the rated power output (not CEA-2006 conditions) is 95 dB.

2-Ohm Stable: The amplifier can support a 2-ohm load when not bridged; the 2-ohm power output is 60 watts RMS x 4 channels.

Bridgeable: Either side (or both sides) of the four-channel amplifier can be bridged to a 4-ohm mono load; the bridged output is 130 watts x 2 channel RMS.

Cast Aluminum Heat Sink: The KAC-2404S utilizes a cast aluminum heat sink design to ensure the amplifier stays cool.

Protection circuitry: The amplifier features protection circuits that will turn the amp off in case of the following events:

  • speaker output contacts ground
  • speaker wire short-circuits
  • unit malfunctions and DC is sent to speaker output

Power Indicator: When the amplifier is turned on the Power indicator (on top of the amp) lights up red. This indicator turns off with the amplifier, and will turn off if the amplifier goes into protect mode.


Gain: The A and B sides of the amplifier have independent input gain controls; both 0.2-5.0 volts (RCA).

High Pass Crossover: The A side of the amplifier has a fixed 80 Hz, -12 dB/oct high-pass filter which can be turned On or Off.

Low Pass Crossover: The B side of the amplifier has a continuously variable (50-200 Hz) low-pass crossover. The slope is -18 dB/oct and the crossover can be turned On or Off.


Power Connections: The power and ground connections are 0.55" wide screw terminals; the remote turn-on connection is a 0.35" wide screw terminal. A Phillips-head or flat blade screw driver (not supplied) is required to tighten/loosen the terminals. Spade connectors are recommended. Minimum 10 gauge wire is required for power and ground.

Speaker Outputs: The four pair of speaker outputs are 0.35" wide screw terminals. A Phillips-head or flat blade screw driver (not supplied) is required to tighten/loosen the terminals. Spade connectors are also recommended for the speaker wires.

Note: Each set of speaker output terminals can be used in stereo or bridged mode.

Line Level Inputs: The KAC-2404S' A and B sides each have stereo RCA line-level inputs with independent gain (Input Sensitivity) controls. The inputs will accept signals of 0.2 volts (200mV) to 5.0 volts.

Speaker Level Input: A five-pin (four channel) harness is included for the speaker level input. The input harness is common ground; it will not accept floating ground outputs.

Fuse: The amplifier uses a 30-amp ATO blade-type fuse.

Warranty Note

Warranty Note: This refurbished Kenwood product carries a 90-day warranty when purchased from Crutchfield. Kenwood offers Crutchfield customers an extra 60 days extended warranty beyond the 30-day Kenwood Limited Warranty for Refurbished Product that comes in the box.

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.