A tricked out system calls for a kickin' amp, and nothing fits the bill like a KX series amplifier from Kicker! These high-end amps set the standard for clean, steady sound with MOSFET power supplies and rock-solid construction.

With its unique 3-channel design and 420-watt (at 2 ohms) dedicated subwoofer output, the KX550.3 is an excellent "all-in-one" amplifier that lets you drive a pair of full-range (or component) speakers and a subwoofer simultaneously. And with 70 watts of RMS power going to each of the front channels, you don't have to worry about clarity or volume either.

Take full control of your sound with the dash-mountable KickBass remote that puts between 0 and 18 dB of bass boost at your fingertips. Variable high- and low-pass filters (from 50-200 Hz) let you tune the sound for your setup, and three-way protection circuits guard against overvoltage, reverse voltage, and overheating.

Product Highlights:

  • 70 watts RMS x 2 + 210 watts RMS at 4 ohms (14.4 volts)
  • 85 watts RMS x 2 + 420 watts RMS at 2 ohms (14.4 volts)
  • speaker- and preamp-level inputs
  • variable high- and low-pass filters (variable 50-200 Hz, 12 dB per octave)
  • variable bass boost (0-18 dB) centered at 40 Hz with wired remote control
  • three-way protection circuitry
  • cooling fan
  • requires 4-gauge power and ground leads and a 60-amp fuse — wiring and hardware not included with amplifier
  • 19-3/16"W (15-3/4" without endcaps) x 2-9/16"H x 9-15/16"D
  • warranty: 2 years
  • 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.

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Hands-on research

What's in the box?

Download owner's manual

  • Three-channel amplifier with two 30-amp fuses inserted in chassis
  • 2 EndKaps (installed)
  • 2 Spare 30-amp fuses
  • 6 Spade terminals
  • Remote bass level control
  • Mounting bracket
  • 2 Self-tapping screws for mounting remote level control (3/8" length)
  • 19.25' Remote bass control cable (with RJ-14 plugs on each end)
  • Four self-tapping screws (#8 x 7/8")
  • 3mm Allen wrench
  • 12" Speaker-level input harness (with 4-pin Molex plug on one end)
  • Owner's Manual
  • Warranty Registration Card (return for free Kicker decal)
  • Kicker Certified Power Certificate

Product Research

Inputs and Outputs Notes


Class AB/D Amplifier: The hybrid design of the Kicker KX550.3 amplifier combines the sound quality of "AB" amplifiers for the stereo section (called "Amp 1"), and the efficiency of "D" amplifiers for the subwoofer section.

EndKaps: The amplifier features two removable, cast aluminum EndKaps that are mounted to each end of the amplifier. These EndKaps protect and hide all of the wiring connections to the amplifier, and must be removed before the amp is mounted. The EndKaps can be prepped and painted any custom color you choose. They are mounted to the amp with 4 Allen-head screws (3mm Allen wrench supplied).

Forced Induction Cooling: To keep the amplifier cool, the amplifier utilizes a forced induction cooling system. When the internal temperature reaches a preset temperature, the built-in fan automatically turns on to exhaust the hot air through the top vents and draw in cool air from the side vents. As the temperature rises, the fan spins faster, circulating more air to cool the amplifier.

Top-mounted Controls: The KX550.3 features five rotary controls on the top panel: input gain control, bass boost control and crossover frequency control for the sub section, and input gain control and crossover frequency for the stereo amp section. These controls can be easily accessed, even with the EndKaps installed.

Variable Low-Pass Filter: The amp is equipped with a full-time variable low-pass filter for the sub section which prevents unwanted high frequencies from reaching your woofers. The cutoff frequency is continuously variable from 50 to 200Hz with a 12dB/octave slope.

Variable High-Pass Filter: In addition to the low-pass filter for the subwoofer section, the "Amp 1" section features a defeatable high-pass filter. the cutoff frequency is continuously variable from 50 to 200Hz with a 12dB/octave slope. A switch on the side of the amp allows you to turn off the filter for full-range operation.

KickBass Bass Boost: The KickBass bass boost circuit provides up to 18dB signal boost at 40Hz.

Remote Bass Level Control: The dash-mounted remote unit allows you to adjust the output level of the amplifier. A 19.25' cable is included to allow you to control a trunk-mounted amp from the front of the vehicle. Dimensions: W=2.2", H=1.186", D=1.736" (2.114" including the knob).

SORT Protection Circuitry: The SORT (Short circuit, Over-voltage, Reverse polarity, Thermal) protection circuitry guards against accidents and undesired operation. If the red Protection LED illuminates, SORT protection has been engaged and the amplifier is in protect mode until the problem is resolved.

Kicker "Living Loud" Certified Power Certificate: The amplifier comes with a certificate that indicates the total maximum wattage of your specific amplifier, along with the model number, serial number, tested date, and whether the amplifier passed the total harmonic distortion, signal-to-noise ratio, and protection circuit tests. In most cases, the amplifier's certified power output surpasses the rated power.

Inputs and Outputs Notes

Gold-plated Connectors: The KX550.3 uses custom-tooled, gold-plated connectors to assure maximum power transfer and damping.

Set-Screw Power Terminals: The power and ground set-screw terminals can accept up to 4-gauge bare wire. The remote turn-on set-screw terminal can accept up to 12-gauge wire. A 3mm Allen wrench is provided to tighten/loosen the set screws.

Speaker Terminals: The amp utilizes terminal strip speaker terminals for the three speaker outputs. Six 12-gauge crimp-on spade connectors are included with the amp.

Speaker-level Inputs: High-level input connections are included to allow use with a factory radio or other receiver without RCA preamp outputs. A 12" speaker-level input harness with a 4-pin Molex plug on one end is provided. The receiver's speaker wires will need to be spliced to the bare wires on the speaker-level input harness.

Line Inputs: Two pairs of RCA line inputs are provided to allow you to separately feed preamp signals to the stereo section and the sub section. There are no line outputs on this amp. Note: The line-level and speaker-level inputs should never be used at the same time.


Power Output:

  • Input Voltage at 14.4 Volts:
    • Amp 1 Section (1% THD+N)
      • 70 watts x 2 RMS into 4 ohms
      • 85 watts x 2 RMS into 2 ohms
    • Sub Section (1.5% THD+N)
      • 210 watts x 1 RMS into 4 ohms
      • 420 watts x 1 RMS into 2 ohms
  • Input Voltage at 12.5 Volts:
    • Amp 1 Section (0.085% THD+N)
      • 40 watts x 2 RMS into 4 ohms
      • 70 watts x 2 RMS into 2 ohms
    • Sub Section (1.5% THD+N)
      • 180 watts RMS into 4 ohms
      • 360 watts RMS into 2 ohms

      Note: The Amp 1 section is not bridgeable.


  • Without EndKaps: Width=15.75", Height=2.301", Depth=9.503"
  • With EndKaps: Width=19.1875", Height=2.519", Depth=9.913"

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.