Was: $899.95
Now: $399.95
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Wish that you could find a great deal on a high-performance amplifier that will run your entire system? The Infinity Kappa 255a is the ultimate multi-channel monster amp, and the good news is that we were able to grab a limited supply of them at killer prices.

Housed within the sleek aluminum frame, you'll find five channels of amplification — four channels (50 watts RMS each) for full-range, midrange, or high-frequency reproduction and one highly-efficient, 200-watt subwoofer channel. A unique, sliding power supply gives the amp the broader output range of unregulated power, yet still ensures that it achieves its rated power even with every vehicle accessory running.

You want versatility? The front and rear channels feature built-in crossovers (switchable high/low-pass, 32-320 Hz). If you are biamping a component system, you can switch the front channel crossover to high-pass (480-4800 Hz) and rear channel to band-pass (for your midrange frequencies). The subwoofer section boasts a low-pass crossover (32-320 Hz) and Infinity's Dynamic Bass Optimizer, an extremely sophisticated bass boost that gives you control of both the bass roll-off frequency and the amount of boost.

The elegant Kappa 255a can handle any situation that might arise, from the simple four speaker/subwoofer setup to a more sophisticated 3-way setup with separate mids and tweeters. Since extensive crossover and bass-shaping capability is built in, you don't need to buy any outboard gear. And think of the money you'll save with a single-amp installation.


  • 2-, 3-, 4-, 5-channel, or Tri-way output
  • 75 watts x 4 and 300 watts x 1 at 2 ohms
  • 150 watts x 2 and 200 watts x 1 bridged
  • highly-efficient Class D 200-watt subwoofer section
  • three separate crossovers allow 3-way (sub, mids, tweeters) set-up
  • dual MOSFET power supplies
  • direct connection of 8 gauge power and ground cable
  • variable bass boost (0-8 dB) from 20-80Hz, 12 dB/octave
  • accepts high voltage (up to 9 volts) input
  • 2 year warranty

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

  • Gray-colored amplifier w/ two 40-amp fuses
  • 2 spare fuses
  • Control cover plate
  • 1 weco 2-pin power/ground connectors
  • 1 weco 5-pin speaker/remote connector
  • 2 weco 4-pin connectors
  • 2 cover plate screws
  • 4 mounting screws
  • Manual
  • Warranty/survey card

Product Research





Power output @ 4 ohms: 4 x 50 and 1 x 200 watts
Power output @ 2 ohms: 4 x 75 and 1 x 300 watts
Power output @ bridged 4 ohms: 2 x 150 and 1 x 200 watts
Maximum current draw: 80 A



  • SUB INPUT switch: Can select ext (used when you are connecting a head unit with subwoofer outs) or Int (used when you are connecting a source unit without sub outs, in which case the subwoofer amp signal will be taken from the front and rear RCA inputs.
  • Variable low pass crossover: From 32-320 Hz
  • DBO (Dynamic Bass Optimizer) Controls: Consists of (1) Variable Freq: Can set from 20-80Hz, this is an infrasonic filter which will conserve amplifier power by not attempting to reproduce bass that the woofer can not handle (2) Variable Q control: Will boost the bass by as much as 8dB and can be varied to suit characteristics of bass reflex, free air and sealed enclosures
  • Gain: Continuously variable from .25V to 9V

Rear Amplifier:

  • Rear Input: Can select Front LP (used to turn rear amp to band pass) or EXT to use rear amplifier in any mode except band pass)
  • Mode: (bridged or stereo)
  • Gain: Continuously variable from .25V to 9V
  • Output: Can be set to flat, high pass (used to turn rear amp into a band pass amp) or Low pass
  • Variable crossover: From 32-320 Hz

Front Amplifier:

  • Mode (bridged or stereo)
  • Gain: Continuously variable from .25V to 9V
  • Output: Can be set to Low Pass, High Pass or Flat
  • Variable crossover: From 32-320 Hz
  • X15 switch: Changes crossover frequency range for front amp to 480hZ - 4.8k


  • 3 pairs of RCA gold plated inputs, front/rear and sub
  • There are 4 removable terminal strips (called "WECO" connectors) that the power, ground, remote, and speaker wires must be connected to before they are plugged into the amp. The 2-pin WECO connector accepts up to 8AWG power and ground wires directly. The 5-pin WECO terminal strip is for the remote turn-on and subwoofer speaker connections. The 2 4-pin WECO connectors are for the front and rear speaker connections.


Protection Status LEDs: There is a LED array on the amp that lights green when the amp is on and working properly and lights orange when protection is activated. When the amp first powers up, the LEDs will light orange (until the amplifier finishes a system check), then will light green.

Protection Circuitry: Five levels of protection that monitor the amp and will shut it down if:

  1. the electrical system drops below 10V
  2. the electrical system voltage exceeds 15.5V
  3. the amplifier's temperature exceeds 194 degrees (90 degrees Celsius)
  4. there is a shorted speaker/speaker lead
  5. current draw exceeds product specifications

Note: Cover is made of a see-through Plexiglas tinted green

Our Product Research Team

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