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Sturdy internal components

Diamond Audio D600.4

From the outside, the uncommonly heavy aluminum chassis with its cool flying D logo tells you that this Diamond Audio amp is something special. And when you consider what's inside — high-grade components mounted on military-spec multi-layer circuit boards — you'll know you're looking at an amp that's built to last.

4-channel versatility

The Diamond D600.4 4-channel amp sends 90 watts RMS of clean, pure music to each of your vehicle's front and rear full-range speakers, with no audible coloration or distortion. Bridge this versatile amp to 2-channel mode to run a pair of subs, or you can set the rear amp channels into bridged mode to run a subwoofer with 300 watts RMS of killer bass, while still sending 90 watts to each of your front speakers.

Heat management

heatsink system Overheating destroys an amp's sound quality and longevity. Diamond's designers developed the focused mass heatsink, which draws heat away efficiently by attaching 75% of its mass directly to the components that create the most heat. The amp's output transistors also mount to the heatsink using a special system that provides better heat flow than commonly used clips.

More features that ease setup

The D600.4 features separate high- and low-pass filters and bass boosts for the front and rear channels, so you can tune it for a wide variety of specific speaker and sub systems. A pair of preamp outputs make it easier to add a sub amp when you want, without having to run a new RCA cable to the receiver.

Product Highlights:

  • 4-channel car amplifier
  • 90 watts RMS x 4 at 4 ohms (150 watts RMS x 4 at 2 ohms)
  • 300 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode)
  • separate variable high- and low-pass filters (50-250 Hz, 12 dB/octave) on front and rear channels
  • separate variable bass boosts (0-12 dB at 50 Hz) on front and rear channels
  • focused mass heatsink improves cooling
  • Class AB amp technology
  • PWM MOSFET switching power supply
  • frequency response: 20-20,000 Hz
  • nickel-plated, low-resistance connectors
  • preamp inputs and outputs
  • fuse rating: 40A x 2
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 17-1/16"W x 2-5/16"H x 8-11/16"D
  • 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.

Diamond Audio D600.4 Reviews

Hands-on research

What's in the box?

Download owner's manual

  • 4-Channel amplifier
  • Four 40 amp ATO fuses (2 installed/2 extra)
  • Four 5/8" Self-tapping screws
  • 4 Split lock washers
  • 4 Flat washers
  • Installation manual
  • Diamond Audio logo badge (adhesive backed)

Product Research



Multi-Channel Design: The Diamond Audio D600.4 is a 4-channel amplifier, basically two independent 2-channel amplifiers built into one chassis. Either side can be bridged so it can be used as a 4-channel, 3-channel, or 2-channel amplifier. The amplifier is stable down to 2-ohms in stereo, and 4-ohms when bridged.

LEDs: Power and Protection LEDs are located on the side of the amplifier. A blue Power LED illuminates when the amplifier is turned on and operating normally. A red LED illuminates when any of the amplifier's protection circuits engage; thermal, short circuit, or too low an impedance.


Gain: The front and rear input gain settings are independently adjusted to match the incoming signal voltages. The input gains are continuously variable from 150 mV to 5.0 V.

Bass Boost: The bass boost circuits, centered at 50 Hz, can be independently applied to the front and rear channels. The adjustments are variable from zero to +12 dB.

Crossover Switches: There are also independent crossovers for the front and rear channels; each can be set to LP (low-pass), Full (full range), or HP (high pass).

Crossover Frequency: You can independently select the crossover frequency for the front and rear channel crossovers; each is continuously variable from 50 to 250 Hz. The crossover slopes are 12 dB/oct.


Power Connections: The power and ground terminals are nickel plated set screws and will accommodate up to 4-gauge wire. The remote turn-on terminal will accept up to 8-gauge wire. 4mm (power and ground) and 2mm (remote) Allen wrenches (not included) are required to tighten/loosen the terminals.

Speaker Terminals: The nickel plated set screw speaker terminals will accept up to 8-gauge wire. A 2mm Allen wrench (not included) is required to tighten/loosen the terminals.

RCA Inputs: The D600.4 features two pair of RCA input jacks for easy connection to the source unit's line level output. The RCA input jacks are nickel plated to resist signal degradation caused by corrosion.

RCA Outputs: The amplifier also features a pair of Pass-Thru RCA jacks, providing a convenient method of daisy-chaining an additional amplifier without running an extra set of RCA cables from the front of the vehicle. The RCA output jacks are nickel plated and are unaffected by the D600.4's crossover and bass boost circuitry.

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.