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Rockford Fosgate Punch P400X4

4-channel car amplifier — 50 watts RMS x 4

11 Reviews | 7 questions - 13 answers


Our take on the Rockford Fosgate Punch P400X4

Rockford Fosgate's Punch P400X4 amplifier can put out 50 watts RMS to each of your front and rear speakers, plenty of power for clean music even at high levels. You can use the amp's high-pass filter to remove low bass from your speakers so they'll play more efficiently. You can also switch this amp into 2-channel mode to drive a couple of subwoofers with up to 200 watts RMS each. The amp's low-pass filter comes in handy for getting the right sound from your sub/enclosure combo. The Punch EQ2 includes bass and treble boosts, in case you want to add some boom and sizzle back into the mix.

Big power for your speakers or subwoofers

Rockford Fosgate's Punch P400X4 amplifier can put out 50 watts RMS to each of your front and rear speakers, plenty of power for clean music even at high levels. You can use the amp's high-pass filter to remove low bass from your speakers so they'll play more efficiently. You can also switch this amp into 2-channel mode to drive a couple of subwoofers with up to 200 watts RMS each. The amp's low-pass filter comes in handy for getting the right sound from your sub/enclosure combo. The Punch EQ2 includes bass and treble boosts, in case you want to add some boom and sizzle back into the mix.

Easy to set for optimum performance

P300X2 control panel shown as example

P300X2 control panel shown as example

Once again, Rockford Fosgate steps away from the crowd with their C.L.E.A.N. technology (Calibrated Level Eliminates Audible Noise) — a setup system that ensures your music will sound as clean and powerful as possible. It works like this: play the setup tone on the included test CD, adjust the receiver volume until a red clip light on the amp goes out, then turn the amp gain up until a blue light comes on. It's that simple — your amplifier is now set to match your receiver's output. When your receiver reaches maximum clean volume, you'll get maximum clean power from your Punch amp. At quiet listening levels, you'll hear less background noise and more of your music.

Keeps an eye on things while playing

If that blue light turns solid red while you're playing music, the amp's telling you that your source is distorting and you should turn it down, or risk damage to your gear. The amp's built-in computer keeps tabs on the output current, ensuring that plunging speaker impedances (they change during play) or even a short circuit won't hurt anything.

Maintaining coolness raises efficiency and lowers distortion

Rockford Fosgate's Dynamic Thermal Management system uses forced air to dissipate heat evenly across the amp and out through the high-mass heatsink, efficiently drawing heat away from vital internal parts. Their proprietary MEHSA cooling process maximizes the heat transfer from the MOSFET devices to the heatsink, allowing the heat to escape more readily, so the transistors stay cooler and work better.

Rockford Fosgate P400X4

                                                     P400X4 connection panel and input clip light

Product Highlights:

  • 4-channel car amplifier
  • 50 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 bridged at 4 ohms (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • variable high- and low-pass filter filter (50-250 Hz, 12 dB/octave)
  • variable PEQ2 bass/treble boost (0-18 dB at 45 Hz and 0-14 dB at 12.5K Hz)
  • C.L.E.A.N. gain setup system includes test tone CD
  • test tones also available as MP3 download from Amazon On Demand, Rhapsody, Google Play, and Spotify, labeled "3sixty.3 setup disc" (Punch amps and the 3sixty.3 use the same test tone tracks for setup)
  • Class-AB amplifier design
  • frequency response: 20-20K Hz
  • Dynamic Thermal Management and MEHSA MOSFET cooling systems
  • MOSFET power and output stages
  • preamp and speaker-level inputs (speaker wire to RCA adapter required for speaker-level input)
  • signal-sensing turn-on with speaker-level inputs eliminate need for remote turn-on lead
More Info:
  • 4-gauge power and ground leads and an 60-amp fuse recommended — wiring and hardware not included with amplifier
  • no onboard fuses — when installing multiple amps in a system, an additional 60-amp in-line fuse between the distribution block and the amplifier is recommended
  • 11-1/8"W x 2-7/16"H x 8-13/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

I was very impressed with this purchase. I had a older Rockford fasgate amp that was a 1500 four channel, it finally gave out. This amp is nice and clear with no distortion at high volume, the older amp got distortion at high volume, can't go wrong with this amp

Tracy, Decatur, IL

What's in the Box:

  • 4-Channel amplifier
  • Four 1-1/2" Self-tapping screws
  • 2.5mm Allen wrench
  • Quick setup instructions
  • Certificate of Performance
  • Setup/Manual disc

Rockford Fosgate Punch P400X4 Reviews

Average Customer Review(s):

(11 Reviews)

Rockford Fosgate Punch P400X4

Tracy from Decatur, IL on 10/12/2017

Crutchfield Customer Review (What's this?)

I was very impressed with this purchase. I had a older Rockford fasgate amp that was a 1500 four channel, it finally gave out. This amp is nice and clear with no distortion at high volume, the older amp got distortion at high volume, can't go wrong with this amp

Pros: Nice and clear no distortion at high volume

Cons: With the clarion navigation deck, i couldn't get the amp to line out like my sub amp Rockford fasgate 1000bd

Good for the money

John from Yorkville, IL on 8/18/2017

Crutchfield Customer Review (What's this?)

This thing puts out all the power it advertises and for the price,pretty cleanly! I set my gains with an oscilloscope and the clipping light matched perfectly with the distorted sine wave so that was extra assurance that I set the dial correctly.I have it bridged and powering two 6.5's in the doors.They are way overpowering my sub at this point which was expected because my sub is only getting 300 watts.No complaints with this amp so far!

Pros: Good value

Cons: Gets a bit hot when playing for a long time but that's expected from a class AB amp.

Rockford Fosgate Punch P400X4

Anonymous from Wv on 12/24/2016

Crutchfield Customer Review (What's this?)

Great amp can't go wrong with Rockford amp



2001 jeep TJ

Stuart from Nashville, TN on 8/28/2016

Crutchfield Customer Review (What's this?)

Very satisfied Good upgrade for my system

Pros: Easy install and setup


Punch amp delivers K.O.

Karl from Dundas, MN on 7/5/2016

Crutchfield Customer Review (What's this?)

It has been years since I have upgraded a car stereo but I have always been loyal to Rockford Fosgate. This amp is the perfect amplifier for those that are looking to take their factory stereo to the next level. I was really surprised at just how much more power this amp puts out over the factory head unit. I used to turn my stereo up to 20 before I could hear it clearly. Now I can hear it clearly at volume level 6. Hats off to RF for making excellent products.

Pros: Adds clean undistorted power loud built in crossovers

Cons: None yet

Never Going Back

Sir Shops-a-lot from Northeast Texas on 5/31/2016

Crutchfield Customer Review (What's this?)

I can't believe I thought powering my speakers through the Pioneer head-unit sounded good. This Rockford Fosgate amp is a revelation. Not so much in loudness but in liveness and immersive sound. I run it through Focal Integration speakers, which had a "colored" sound when powered by the head-unit. Through this R-F amp the Focals have clarity and vehicle-filling sound. I think this amp and speaker combination adds to the liveness effect, given that Focals have a reputation for "revealing" sound. Recordings I have heard for years have a fresh perspective, especially over HD radio.

Pros: The featured Trans-ANA circuitry is a deal-maker.

Cons: I think a bypass switch for the punchEQ and crossover circuitry would be nice. I'm a flat-EQ listener and also the Focals are pretty punchy already.

Good amp

Raja from fredericksburg, VA on 3/6/2016

Crutchfield Customer Review (What's this?)

Good amp for the money.



Rockford Fosgate Punch P400X4

Brandon T from Mt Vernon, IL on 2/24/2016

Crutchfield Customer Review (What's this?)

Installed this amp to power my component speakers. 2-6x9's and 2-6 3/4" speakers. Super easy to install, and the SMART no clipping is really easy to setup. Sits very nicely under my passenger seat.

Pros: Super easy setup, enough power for component speakers. Sounds AMAZING!

Cons: Using the SMART clipping setup, i felt the speakers were a bit under powered. I increased gain a bit above their recommended level and now it sounds good.

no complaints

joseph from humble, TX on 1/24/2016

Crutchfield Customer Review (What's this?)

bought the p400x4 to power a set of p1675 components for the front and a set of p16 coax in the rear. it works great in my set up and the c.l.e.a.n. system makes it easy to set the gains

Pros: good for the money

Cons: none so far

Great bang for the buck!

Anonymous from Washington on 12/29/2015

Crutchfield Customer Review (What's this?)

I got this amp on sale. At that price point it is a truly excellent performer. Musically solid with very little coloration and decent power for a nice set of components in the front and co-ax in the rear.

Pros: - High performance for the price - Good power and clarity

Cons: - At this price point I really can't complain. It certainly isn't a high-end 4-channel amp, but it performs at a good mid-level for a good sale price.

very nice piece of equipment

brandon from Middletown ct, on 12/26/2014

Crutchfield Customer Review (What's this?)

Works very well, I love the auto setup of tuning it so yur speakers aren't clipping or getting any distortion and I personally think that there putting out a lot more power than 50rms id say more like 75 80 great amplifier




Hands-on research

Product Research



CEA-2006 Compliant: CEA-2006 is a system of testing and measurement methods for mobile audio amplifiers. This voluntary standard advocates a uniform method for measuring an amplifier's RMS power output and signal-to-noise ratio. The criteria for measuring power uses a DC input voltage of 14.4 volts and the RMS power output is measured with 1% or less Total Harmonic Distortion plus noise (THD+N) over a frequency range of 20 Hz to 20 kHz (for full range amplifiers). Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4Ω. CEA-2006 allows consumers to compare car amplifiers and receivers on an equal basis. Using CEA-2006 criteria, the Rockford Fosgate P400X4 is rated as follows:

  • Power Output:
    • 4Ω: 50 watts x 4-channels
    • 2Ω: 100 watts x 4-channels
    • Bridged: 200 watts x 2-channel (into 4Ω)
  • Signal to Noise Ratio: 85 dBA (105 dB at rated power)

Cast Aluminum Heatsink: The cast aluminum heatsink dissipates heat generated by the amplifier's circuitry. The inherent advantage of casting provides a 30% cooling improvement over conventional extrusion heatsink designs.

Dynamic Thermal Management (DTM): DTM evenly distributes excess heat across the amplifier's entire heatsink.

MEHSA³ (Maximum Efficiency Heat Sink Application-3rd Generation): MEHSA is a Rockford Fosgate proprietary process that increases the heat transfer from the MOSFET devices to the heatsink. The multi-layer insulated metal MEHSA substrate operates with minimal thermal resistance, spreading heat both downward and outward to quickly dissipate heat from each device across the heatsink. This allows greater power output, enhanced thermal stability, and maximum reliability.

Trans-ANA (TRANSconductance Active Nodal Amplifier): Trans-ANA is a circuit that allows the audio signal to pass through the amplifier at low voltage. The signal is directly level-shifted to the fixed high voltage rails via a pair of drive transistors. Signal linearity is assured by an active node formed by the drive transistors at ultrasonic frequencies. The result is crystal clear sound quality.

NOMAD (NOn-Multiplying Advanced Decision): NOMAD is an intelligent protection circuit that uses an analog computer to make real time decisions regarding temperature, voltage, current and impedance. The amplifier is protected without limiting sound output unless needed.

DSM (Discrete Surface Mount): High speed robotics are used in the manufacturing process to place 1% tolerance parts and large board traces. DSM improves the efficiency of the circuit, decreases cross-talk from other discrete components and lowers operating temperature.

CLEAN Set-Up: Rockford's integrated level setting technology, CLEAN (Calibrated Level Eliminates Audible Noise), replaces sophisticated test equipment with input/output clip LEDs, allowing you to match the source unit's output to the amp's gain, and optimize the amp's output. The input clip indicator works in conjunction with the audio source volume, illuminating red when the source reaches it's clipping point. The output clip indicator works in conjunction with the input level dial on the amp, illuminating the appropriate color depending on the audio content used for the setup.

Power and Protection LEDs: The LEDs are located on top of the amplifier. A blue Power LED illuminates when the amplifier is turned on. A red Thermal LED illuminates if the amplifier overheats. The yellow Protect LED illuminates if a short circuit or too low an impedance is detected at the speaker connections. When any of the protection circuits engage, the amp automatically shuts down until the problem is corrected.

Balanced Differential Inputs: Differential inputs eliminate noise picked up by signal cables by measuring the voltage of both the (+) and (-) input signal, then subtracting the voltage common to both conductors (noise), resulting in only the clean signal entering the amplifier.


Input Level: The front and rear sections of the amplifier have separate input level controls. To accommodate the varying range of signal levels from today's factory and aftermarket radios, the input levels are adjustable from 150mV to 12V.

Crossover: The amplifier's internal crossovers are also independent for the front and rear channels. The slope is 12 dB/octave and both can be set to high-pass, all-pass (full range), or low-pass operation. The crossover points are variable from 50 Hz to 250 Hz.

Punch EQ: Both the front and rear amplifier sections have Punch EQ circuits, the function of which changes with the crossover switch. When the crossover is set to low-pass, the Punch EQ acts as a variable bass boost; 0-18 dB at 45 Hz. When the crossover is set to high-pass, the Punch EQ acts as variable treble boost, 0-14 dB at 12.5 kHz. When the crossover is set to all-pass, both the bass and treble boost circuits are active.

Input Switch: With the input switch in the 2-channel position, connecting only the front inputs will send the signal to both the front and rear sections of the amplifier. In the 4-channel position, both front and rear inputs must be used.


Power Connections: The power and ground terminals are nickel-plated captive c-clamp wire connectors and will accommodate up to 4-gauge wire. An external 60-amp fuse (not included) must be installed on the power wire. The remote turn-on terminal will accept up to 12-gauge wire. A Phillips or flat-head screwdriver (not supplied) is required to tighten/loosen the terminals.

Speaker Connections: The four pair of speaker output terminals are also nickel-plated captive c-clamps and will accept up to 8-gauge wire. A Phillips or flat-head screwdriver (not supplied) is required to tighten/loosen the terminals.

Signal Input: The front and rear RCA inputs will accept either a line-level or speaker-level input. A speaker-level signal can be connected using a Speaker Wire to RCA adapter (sold separately). When using a speaker-level input signal, the auto turn-on feature is active and the remote turn-on terminal becomes a 12 volt output to turn on/off up to two additional amplifiers or other components.

Our Product Research Team

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Staff Reviews

Product reviews from the Crutchfield Labs

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Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

It was the best amp for what i needed it for and the cost [ Tracy  Sep 29, 2017 ]
Due to it is capable of driving the front 2 speakers and the subwoofer,l when 2 channels are bridged. [ W  Sep 20, 2017 ]
good reviews from other customers and good experience with other Rockford Fosgate amplifiers. [ MICHAEL  Sep 10, 2017 ]
This was the toughest pick and I hope Fosgate does not disappoint.This will be bridged to 2 channels strictly running midrange/bass on 6.5 speakers in doors. [ John  Jun 18, 2017 ]
Bought this amp to use with my factory head unit. Built in crossover was a plus. [ Evans  Oct 22, 2016 ]
I have had it before and it is a great amp. [ Joseph  May 22, 2016 ]
Size and features. The anti clip set up is a nice feature. [ MICHAEL  Feb 05, 2016 ]
Rockford Fosgate has a reputation for consistent quality and excellent power output. There latest amps do not disappoint. [ Chance  Dec 26, 2015 ]

7 questions already asked

I don't see why you could not just hook it the way your thinking you would.... For it does not hert to try it... That's what I am thinking... Since I try things to see if it works...?? [ Kent  Jun 24, 2017 ]
And still use the other channel for stereo regular separation just change your frequencies for each chanel. Run your gains about 1/2 [ Hector  Jun 23, 2017 ]
Yes, as long as your speakers in the rear equals 2 ohms per side. Give or take a few, 1.8 or 1.7 would be fine. Just remember each speaker that is added cuts your power per speaker down. Say the amp does 100 watts at 2 ohms, 2 speakers on the rear right would be 50 per speaker, if you did 3 speakers on the right, and the ohm load was the same, you only have 33 watts per speaker. [ DAVID  Jan 21, 2017 ]
Hello, I used my p400x4 in a Toyota tundra. In my particular configuration I left the front channels untouched and added this amp to power the rear door components I installed, and a JL 8" loaded enclosure under the rear seat. I bridged one side of the amp to run that single voice coil 4 ohm JL sub and set the crossover at @50 hz. I have the gain set about half way. I ran the other side of the amp to power some basic MTX 6.5" components in the rear doors. Here's a problem you might experience, even with the components set at @65 hz (only playing frequencies above that point) and the gain about 75%, the clipping light flickers at higher volumes. The way I have it set up now is the way I like it to sound, so im ok with it clipping a little bit at higher volumes with songs that have a lot of bass. I cant hear any real distortion, but you know if that clip light is flickering, it probably is a little. The bridged sub channel doesn't clip at all. So, with you wanting to run 2 sets of components off one side of the amp, it's probably going to clip. I love your idea though, I've always wanted to try that set up to see how it would sound. Maybe with those higher quality focals they might be more efficient and not cause problems, but you never know till you try. I would try it and see, install everything loosley to tune it, and if it clips too much, maybe come up with a different plan. I like the amp, it sounds good, has decent power and tuning options, usual RF quality. There is always some combination that will work, hope this helps. [ Josh  Jan 21, 2017 ]
I would recommend the p600x4 to get the most out of the speakers. The p400x4 would work too just wouldn't be as loud or hard hitting as the 600. [ TREVOR  Feb 18, 2015 ]
I like mine. Has plenty of power. I don't have a subwoofer. [ Bobby  Feb 17, 2015 ]
I replaced factory speakers. I can't compare them to yours but I like them. Just remember that the Twitters are separate and have to be mounted separately. [ Bobby  Feb 17, 2015 ]
no. it does not [ RICHARD  Jun 22, 2014 ]
No it doesnt [ BRIAN  Jun 17, 2014 ]
Yeah, you can. But honestly I would just go buy the P300X2, and a mono block for your sub. Bridging for the sub on this amp will only give you like 250 watts rms to your sub. And that's like...max. Also I'm not entirely sure if you can make 2 channels high pass, and the other 2 low pass. Just be sure you buy a 2 ohm DVC sub if you're going to bridge it. [ Luke  May 24, 2014 ]
If you want to know what an amps real power output is. Multiply the fuse rating by 10. If the amp call for a 25 watt fuse, your looking at a 250 watt amp, (give or take, I know most systems are 14.4 volts, it's easier to multiple by 10 than it is 14.4) even thou it may say 1000 watts on it, Ohm's Law dictates that, now there are a few new amps out there that use capacitors to get around that, but you pay for that technology, Fosgate has a few examples of them. [ DAVID  Jan 21, 2017 ]
All of our products display the RMS power ratings. This provides a more real world ideal of the power you will get from the unit and avoids the numbers game that gets played with Peak power. You can find some good tips on choosing speakers here: [ Jeff  Feb 08, 2014 ]  Staff