Whether you're building a component system, powering a pair of full-range speakers, or just pounding away with a subwoofer, there's an Infinity Reference series amp ready to take on the job. Boasting impressive power ratings and fine-tuned controls, these amplifiers are capable of sending your music to new sonic heights.

It's all thanks to high-output MOSFET power supplies — which ensure maximum power delivery to your speakers for efficient operation — and variable filters that let you contour the output to fit your music. And, since every Infinity Reference amplifier is CEA-2006 compliant, you'll know you'll get the power as advertised.

Whatever your power needs, the versatile Infinity Reference 7540a multi-channel amplifier can take care of them. With 111 watts RMS x 4 channels, it can easily drive two sets of full-range or component speakers. Or, you can bridge the channels to stereo mode, and send 278 watts RMS each to a pair of subwoofers or component speaker system.

Product Highlights:

  • 4-channel car amplifier
  • 111 watts RMS x 4 at 4 ohms (139 watts RMS x 4 at 2 ohms)
  • 278 watts RMS x 2 at 4 ohms in bridged mode (4-ohm stable in bridged mode)
  • 2-, 3-, or 4-channel output
  • variable high-/low-pass filters (32-320 Hz, 12 dB/octave)
  • variable Bass EQ (0-12 dB @ 50 Hz)
  • CEA-2006 compliant
  • preamp- and speaker-level inputs
  • preamp outputs
  • 8-gauge power and ground leads recommended — hardware and wiring not included with amplifier
  • 16-3/8"W x 2-11/16"H x 12-1/8"D
  • fuse rating: 30A x 2
  • warranty: 1 year
  • 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.

Infinity Reference 7540a Reviews

Average Customer Review:

4 reviews
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Infinity 7540a amplifier

Written By psun, 98311 on Monday, May 26, 2014

I recently aquired one of these amps used. I hooked it up to a set of Kenwood separates (front/stereo) and a single 4 ohm 10 driver (rear/bridged). The mids/tweets are very clear while that single Kicker Comp 10" in a sealed box @ 278w literally shakes the seats; this system was for my daughter who primarily listens to rap/dance. All of her friends are shocked by how loud and clean her system is.

Pros: Price, sound very musical, I am shocked at how hard the bridged channel can power the base!

Cons: It is a very large amp which makes it a challenge to install.

this amp is great

Written By illwill, fontana, ca on Saturday, November 26, 2011

i got this amp used for 20 dollars. hooked up in my car and was very surprised with the power it has. it pushes 2 10" infinity subs. the bass is perfect. sounds nice and clear, and when you want to bass slap someone you can do that as well. i highly recommend this amp to anybody. great value for the amount of joy you will get from this amp

Pros: price is exceptional, 4 channels. and of course the "POWER"

Cons: there is nothing that isn't likeable on this amp

Nice for the price

Written By mailman, Columbia, MD on Monday, January 09, 2006

Crutchfield Customer Review (What's this?)

Very nice. I am running it in 4 channel mode pushing two sets of polk audio speakers. The quality of the sound is beyond reproach. Only problem is that the power/ground block is the plated kind not the block kind so its tough to get a 4 or even 8 gauge wire in there. But overall, very nice.

Good Deal

Written By Greg, stamford,ct on Saturday, December 31, 2005

Crutchfield Customer Review (What's this?)

I have two 10' Infinity References connected to this amp and after playing around with the settings, THEY BUMP!!

This amp is a good deal for the money. Its half the price of the same amp because its refurbished. I had no problems with mine, and the warranty will cover anything.

The only trouble i had was with the bass boost. It only works in the rear setting so if your driving two subs like me, one of them will hit harder then the other.

Hands-on research

What's in the box?

Download owner's manual

  • 4-Channel amplifier with two installed 30A ATC fuses
  • Two 11" speaker-level input harnesses
  • Two 30A ATC fuses
  • 4 Self-tapping screws
  • 1 Silica gel packet
  • One 8" x 2-1/2" Infinity sticker
  • Instructions
  • Amplifier Quick Start Guide
  • Warranty card

Product Research

Inputs and Outputs Notes


Status LEDs: The amplifier has the following status LEDs:

  • Clip: indicates the amplifier is being overdriven, and your speakers may be in danger. This should blink only on musical peaks, and not be on constantly.
  • Power: indicates the amplifier is on
  • Protect: indicates any of the following problems: DC voltage on amplifier output, overheating, under voltage, over voltage, and short circuit in the speakers or wire

Variable Filters: The front and rear channels have separate filters. Each filter can be set for low-pass, high-pass, or full-range operation. In the low-pass and high-pass modes, each filter can be adjusted from 32 to 320 Hz. In each case, the filter has a slope of 12 dB per octave.

Bass Boost: For added low frequency performance, this amplifier has a 0 to 12 dB variable bass boost centered at 50 Hz.

Preamp Outputs: The preamp output jacks provide a convenient source for daisy-chaining an additional amplifier without running an extra set of RCA cables from the front of the vehicle to the amplifier location. These outputs provide a full-range signal.

Inputs and Outputs Notes

Right Side of Amplifier:

  • +12V (power): 0.357" screw terminal
  • Remote: 0.357" screw terminal
  • GRD (ground): 0.357" screw terminal
  • Speakers: 0.357" screw terminals

Left Side of Amplifier:

  • Front High Level Input: 4-pin jack for use with supplied speaker-level input harness
  • Rear High Level Input: 4-pin jack for use with supplied speaker-level input harness

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.