You're greedy — for more power and more convenience! MTX created the Thunder6000 line for you, packing in unstoppable MTX power and a bevy of useful features. The Thunder6304 4-channel amp unleases raging MOSFET power to all your speakers — MTX's pure N-channel design keeps the signal path simple for exceptional sound quality.

The Thunder6304 features built-in variable crossovers to control the range of frequencies going to your speakers. Thunder EQ boosts bass up to 18 dB at 40 Hz for extra thump, and high input capacity (up to 8 volts) will accommodate your receiver's high-voltage preamp output signal with ease. The parallel input switch allows a 2-channel signal to drive all four channels — no "Y" adapter needed.

  • 2-, 3-, or 4-channel output
  • Tri-way capable (Tri-Way crossover required)
  • 150 watts x 2 in bridged mode
  • 75 watts x 4 at 2 ohms
  • requires 4-gauge power and ground leads — wiring and hardware not included with amplifier
  • high input capability (up to 8 volts)
  • PWM MOSFET switching power supply
  • independent gain controls
  • Thunder EQ bass boost (up to 18 dB at 40 Hz)
  • front and rear variable 40-200 Hz high-pass/low-pass crossovers, 12 dB/octave high-pass, 24 dB/octave low-pass
  • preamp outputs
  • 9-5/16"W x 2-1/8"H x 13-15/16"D
  • 1-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

  • Black MTX Thunder 6304 amplifier with chrome trim
  • Three 25-amp blade fuses (installed)
  • Warranty registration and customer survey card
  • Performance certificate
  • Owner's manual (English/French/Spanish/German)
  • Amplifier Input/Output Connections sheet
  • MTX Audio sticker
  • Bridged impedance warning sticker.

Product Research


Inputs, Outputs, & Controls

Wiring Recommendation


Patented PWM MOSFET Switching Power Supply:  This type of power supply is used for maximum power output and protection.

Class A 100% Discrete Driver Circuitry Topology: The preamp stages use Class A topology for low distortion and a high damping factor; the result is tight, controlled bass.

Real-time Computerized Protection Circuit: The protection circuit makes sure you amp is operating within safe parameters for maximum power and protection.

Acoustically Seamless Turn-on/Turn-off: A circuit that prevents turn-on/turn-off "thump" is included to eliminate turn-on/off noise.

Rubber Insulated Iso-Feet™: Four rubber Iso-Feet are attached to the amplifier. The rubber feet let you mount the amp securely, while preventing the mounting screws from coming into contact with the amp's chassis.

Buffered, Isolated RCA Output: In addition to the front and rear sets of preamp inputs, there is a set of full-range summed RCA preamp outputs. The outputs allow you to daisy-chain one amplifier to another.

Intelligent Surface Mount Technology: Features substantially shorter internal and external lead lengths, reducing stray capacitance and inductance, which results in cleaner and more accurate musical reproduction with less noise interference.

Thunder EQ: Thunder EQ is a continuously variable Bass Boost (0-18 dB) centered at 40 Hz. There are two Thunder EQ controls, one for the rear outputs and another for the front outputs, so the boost settings for the front and rear channels are independent of each other. 

Crossovers: This amplifier includes two independent crossovers; one crossover is for the front speaker outputs and the other is for the rear speaker outputs. Each crossover may be set for high-pass, low-pass or full-range output. There is a crossover frequency control, continuously variable from 40 Hz to 200 Hz, for each crossover, so each the crossovers may have different crossover frequencies. When a crossover is set for high-pass operation, it has a 12 dB/octave slope; when set for low-pass operation, a crossover has a 24 dB/octave slope with mono output.

Terminals: The terminals are nickel-plated, heavy-duty screw terminal connectors.

Performance Certificate: MTX tests each amplifier, and the technician records the "actual" power output on the Certified Performance Certificate included with each amp. The amp must meet or exceed the rated specification in order to leave the factory.


Actual RMS Power Rating: The actual RMS power rating into a 4-ohm load is 37.5 watts x 4. The Crutchfield database lists a 4-channel, 4-ohm rating of 38 watts x 4, because the rating has been automatically rounded to the nearest whole number.

Peak (Dynamic) Power (measured at 14.4 Volts DC):  

  • 90 Watts x 4 into 4 Ohms
  • 165 Watts x 4 into 2 Ohms
  • 325 Watts bridged (x2) into 4 Ohms

Inputs, Outputs, & Controls

Left side:

  • Gain controls: independent front and rear gain controls allow you to match the input sensitivity of the amplifier to the particular source unit you are using
  • Thunder EQ Controls: two rotary controls, one for the front channels and another for the rear, that allow you to set the bass boost applied to the speaker output signals 
  • Input Select 2CH/4CH Switch: a pushbutton switch used to match the amp's input to the source unit's output so all four channels of the amp are driven. If your source unit has 2 outputs (a left and a right), connect them to the amp's front channel inputs, and place the input select switch in the 2CH position. Likewise, if you are using a 4-channel source, place the input select switch in the 4CH position. In the 4CH position, the fader on your source unit will operate.
  • Front left and right RCA input jacks
  • Rear left and right RCA input jacks
  • RCA Sum Out Jacks: RCA preamp output jacks, which allow you pass summed, full-range signals from this amplifier to another amp in a daisy-chain configuration
  • X-Over Switches: two switches, one for the front channels and another for the rear, that let you select high pass, low pass, or full range operation for the speaker outputs
  • Crossover Frequency Controls: two rotary controls, one for the front channels and another for the rear, that are continuously variable from 40 Hz to 200 Hz

Right Side:

  • Fuses: slots for three 25-amp blade fuses (fuses are included)
  • Power Terminal: (0.54" wide) designed to accept cables as large as 6 gauge
  • Remote Turn-on Terminal: (0.34" wide) 
  • Ground Terminal (0.54" wide) designed to accept cables as large as 6 gauge
  • Speaker Terminals: (0.34" wide) L (+/-) and R (+/-), Front and Rear; these terminals are configured like steps, with the rear outputs in a row below the front outputs

Wiring Recommendation

Wiring Recommendation: This amplifier uses three 25-amp fuses, so its fuse rating (75-amps total) exceeds that of typical 4 gauge wiring kits, which tend to include a 60-amp fuse. The highest AGU fuse values carried by Crutchfield are 70 and 80 amps. To accommodate the entire 75-amp fuse rating, the fuse included with a pre-packaged wiring kit should be replaced with an 80-amp AGU fuse (sold separately).

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.