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JL Audio XD400/4v2

4-channel car amplifier — 75 watts RMS x 4

17 Reviews | 4 questions - 4 answers


Our take on the JL Audio XD400/4v2

JL Audio's XD400/4v2 amp packs a wallop far beyond what you'd expect from something so small. This compact amp plays your music with true fidelity and impressive impact, without straining your car's electrical system, thanks to JL Audio's proprietary NexD™ amplifier technology. A cast alloy heatsink and an advanced cooling system keep this amp at optimal temperature, eliminating thermal shut-downs so your music keeps going strong without interruption.

Power your system

JL Audio XD600/6v2

Compact design applies to internal components too.

JL Audio's XD400/4v2 amp packs a wallop far beyond what you'd expect from something so small. This compact amp plays your music with true fidelity and impressive impact, without straining your car's electrical system, thanks to JL Audio's proprietary NexD™ amplifier technology. A cast alloy heatsink and an advanced cooling system keep this amp at optimal temperature, eliminating thermal shut-downs so your music keeps going strong without interruption.

Versatile amp

The XD400/4v2 can deliver 75 watts RMS each to 4 full-range speakers, or you can bridge the amp to 2-channel mode to send 200 watts each to a pair of subs. You can also run two speakers with the front channels while driving a subwoofer with 200 watts RMS from the rear channels bridged together.

Works with almost any vehicle's system

"Differential-balanced" inputs keep the signals clear of outside noise, and allow you to connect this amp to just about any in-dash stereo, even a factory radio. The speaker-level inputs feature two auto turn-on modes so you can readily incorporate this amp into a factory system — no need for RCA connections or a remote turn-on lead. An optional wired remote lets you tweak the volume of the whole system from your front seat, or you can switch to the rear channels only, which is handy if you're using them to drive a sub.

JL Audio XD600/6v2

                                           XD600/6v2 connection panel

Product Highlights:

  • 4-channel car amplifier
  • 75 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 bridged)
  • variable low- and high-pass filters (50-500 Hz, 12 dB/octave)
  • optional wired remote controls sub or system level
  • Class D amplifier design with NextD™ switching amp technology
  • differential-balanced inputs eliminate noise coming from your vehicle's electrical system
  • Advanced Rollback Protection System prevents thermal shut-down
Connection Features
  • preamp and speaker-level inputs (speaker wire to RCA adapter required for speaker-level input)
  • high-level inputs — up to 8 volts RMS (about 16 watts)
  • DC offset or signal sensing auto turn-on eliminates need for remote lead
  • preamp outputs
  • 8-gauge power and ground leads and a 40-amp fuse recommended — wiring and hardware not included with amplifier
  • no onboard fuses — when installing multiple amps in a system, an additional 40-amp in-line fuse between the distribution block and the amplifier is recommended
  • 8-9/16"W x 2-1/16"H x 7-1/8"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Four-channel amplifier
  • 2.5mm Allen wrench
  • Self-adhesive JL Audio badge
  • Owner's manual

This small amp is a powerful enough to power 4 component speakers with 75 watts RMS per channel with clear sounding music. I don't have a need for anything more than this little bad boy puts out!

Gerald, Mays Landing, NJ


JL Audio XD400/4v2 Reviews

Average Customer Review(s):

(17 Reviews)

JL Audio XD400/4v2

Crutchfield customer from Stockton, CA on 1/29/2019

Crutchfield Customer Review (What's this?)

Verry happy with my purchase and promp delivery



I love this amp.

Justin from Niceville, FL on 1/13/2019

As stated in the title, I love this amp. I have owned it for three years now and I can't believe the amount of abuse it has taken without a hitch. I've had it installed in three different vehicles now, all with different sound systems. Absolutely amazed with the amount of power this can kick out from such a small package. Easy to install, easy to tune, easy to hide, I just can't think of anything wrong with it. I can't recommend this enough.

Pros: - Stays cool. - Easy to hide due to small footprint. - Sounds great. - Hardy, has taken quite a beating over three years with no issues.

Cons: - Expensive.

JL Audio XD400/4v2

Gerald from Mays Landing, NJ on 10/19/2018

Crutchfield Customer Review (What's this?)

This small amp is a powerful enough to power 4 component speakers with 75 watts RMS per channel with clear sounding music. I don't have a need for anything more than this little bad boy puts out!

Pros: Small size and clean high power

Cons: None

JL Audio XD400/4v2

Daniel from Austin, TX on 5/8/2018

Crutchfield Customer Review (What's this?)

Really good in tight spaces. Quality is always what you expect from JL



JL Audio XD400/4v2

Crutchfield customer from Hercules, CA on 6/15/2017

Crutchfield Customer Review (What's this?)

Top notch JL audio love your products.??



JL Audio XD400/4v2

Jason from Jackson, MI on 5/10/2017

Crutchfield Customer Review (What's this?)

So far so good. It's only been installed for a week but it works very well. I previously had the 300/4 which dropped the right rear channel. I had it repaired by the factory and it lasted a couple of years and dropped that channel again and took the speaker with it. I'm hoping the XF400/4v2 holds up better.



JL Audio XD400/4v2

Richard from Silverton, OR on 3/5/2017

Crutchfield Customer Review (What's this?)

I love this amp! It is half the size of most that put out the same amount of power & draws less on your battery. The sound is clean and the range is fantastic.



JL Audio XD400/4v2

Steven from Roseville, CA on 3/5/2017

Crutchfield Customer Review (What's this?)

I had one of these on my Harley Davidson very small compact with a lot of power. Sounds really good. So I purchased a second one for my Harley Davidson say motorcycle so I have two of these jail audio 400 W four channel amplifier's parents six JBL marine speakers on my Harley Davidson.



Incredible Performance and Quality

Crutchfield customer from North Aurora, IL on 1/31/2017

Crutchfield Customer Review (What's this?)

These amps with new technology are impressive, gone are the days you need a 3 foot long amp to get power and quality. I've owned Alipne, Kicker, MTX, Rockford, PPI, Soundstream, ADS, Hifonics, Pioneer, acoustic, Sony, Profile, amps and I keep going back to JL Audio. I'm hooked for life, just can't beat them.

Pros: incredibly small footprint, amazing sound quality

Cons: made in china

Costly but worth it!

Mar from San Francisco CA on 4/11/2016

Crutchfield Customer Review (What's this?)

I initially had a 4 channel Pioneer amp which I was told would be sufficient to run my Alpine component speakers and Pioneer head unit. I would say for awhile it ran fine but I began to notice some issues with it. I heard static/buzzing noise coming from the tweeter and the sound kept fading from right to left. I eventually brought to the place I had the amp and speakers installed and he told me that the amp was under powered. I still don't know why he didn't tell me when he installed it originally. He recommended I get the JL Audio XD400/4v2 amp. The sound sounds cleaner and tighter. The installer told me not to underestimate the amp. The worse that could happen is that I blow out my components before the amp.

Pros: Cleaner and tighter sound for such a small amp. It's JL..enough said

Cons: Costly but worth it

Great Amp

Bill from san jose, CA on 2/9/2016

Crutchfield Customer Review (What's this?)

I wanted to upgrade the stock stereo in my 2008 Lexus. I started with a Kenwood head unit, which improved the functionality (Bluetooth, phone, UBS, etc) but the sound wasn't much better. I installed Focal 165 front speakers running off the Kenwood head unit amp. The sound was worse than it was with the factory speakers! The speakers distorted and crackled, even at low volume. I assumed that the speakers were faulty. However, my local installer said the Kenwood amp was not adequate to provide a clean signal to the Focal speakers. He recommended this amp. He was right! The Focal speakers superb, driven to perfection by this amp. In addition, I installed a subwoofer. It's also powered by this amp, and sounds great. My message to unsophisticated buyers (like me) is to forget about powering good speakers with a head unit amp. Invest in a high quality, high power amp like this one, and you'll enjoy a great sound system.

Pros: A perfect match for high quality speakers, and subwoofer.

Cons: None.

Big Power, Small Size

John from Simi Valley, Ca on 12/17/2015

Crutchfield Customer Review (What's this?)

This amp is my second JL amp in this model, it's silent, pumps out crazy power and never gets too hot! I would definitely buy this amp again!

Pros: Small size, runs at a cool temperature, amazing power output, and no bright unnecessary lighting

Cons: none

jl audio xd400/4v2

Mike from Roseville,MI on 12/8/2015

This is my very first amplifier from jl audio and very much impressed with the clean sound and quality from this company. The highs,mids and lows come thru flawlessly. It is hooked up to the pioneer deh-x9600bhs head unit along with the pioneer ts-d6802 in the front doors along with the alpine type-r 68 speakers in the rear deck of a1999 ford crown victoria (non-police package). Knowing how clear/clean the sound quality is it is a very powerful amplifier and would highly recommend this amplifier to anyone

Pros: Powerful clean and clear sound quality

Cons: None what so ever

Pppow, power for Thumping Base and Silky-clear Highs

Doug from Oregon on 6/1/2015

Crutchfield Customer Review (What's this?)

Plenty of power to round out even the most dynamic of passages delivering thumping base and silky highs while quiet with low signal to noise ratio and almost no detectable distortion. This Class D amplifier sips power & won't leave you drained and stranded while parked and cranked! I'm not disappointed and you won't be too.

Pros: Powerful, quiet, compact, wide dynamic range and doesn't throw a lot of heat.

Cons: none

Amazing Compact Amp

Joe from Augusta, GA on 5/4/2015

This amp is very compact and packs quite a punch! I am driving four JL C2-650's, components up front and coaxials in the rear doors. I am using a JL 500/1 driving a Stealthbox and it all ties together perfectly. My stereo will ruin your hearing now with amazing clarity. I strongly recommend this amp!

Pros: Compact, powerful, well made, distortion free

Cons: None really other than the price being slightly high but you get what you pay for...

Very nice, well-controlled sound

Chris B. from Texas on 3/8/2015

Crutchfield Customer Review (What's this?)

This amp rocks. I've always swapped out factory speakers, but never installed an aftermarket amp. That approach didn't work too well in my new Accord. So, I bought an Alpine MRV-F300, which had a nice price, but pretty awful sound, at least to me. I wanted something that was more musical. And because I'd already run an 8-gauge power cable for the Alpine, I wanted something that would work with that, so I returned the Alpine and got this. In the end, this JL amp is fed through an AudioControl LC6i and is driving four Alpine SPS-610 coaxials. The sound is really good, though I will eventually upgrade the speakers to something more worthy of this amp.

Pros: surprisingly musical, compact and can run off smaller power cable

Cons: pricey to me

Amazing amp

Crutchfield customer from Upland, ca on 5/25/2014

Crutchfield Customer Review (What's this?)

It is an amazing amp for it's size. I used it to power my sub and two tail gate speakers for tail gating and is perfect.

Pros: Size vs power ratio



Hands-on research

Product Research



XDv2 Series: The JL Audio XDv2 amplifiers feature big audio performance from a small footprint. With advanced NexD switching technologies, the XDv2 amps exceed 80% efficiency, running cooler than most other amplifiers. The Advanced Thermal Rollback System gives you increased reliability and better audio performance by virtually eliminating thermal shut-down. Because the XDv2 amps employ smaller cast alloy heat sinks, they can be installed in smaller spaces. XDv2 amplifiers feature a black powder-coat finish with a brushed aluminum cover for the controls.

Four-channel Class-D Amplifier: The XD400/4v2 is a Class-D 4-channel amplifier, designed specifically for full-range operation, but can be used to power subwoofers. The amplifier is stable down to 2 ohms in stereo, or bridged to a 4 ohm load.

Amplifier Rating: The XD400/4v2 is rated at 75 Watts RMS x 4 channels at 4-ohms (20 Hz to 20 kHz), Signal-to-Noise Ratio of >104 dB (at rated power), 1% THD, @14.4 Volts. At 2 ohms, the rated power is 100 Watts RMS x 4, and bridged at 4 ohms, it outputs 200 Watts RMS x 2.

Advanced Rollback Protection: The XDv2-Series amplifiers employ advanced thermal and low-impedance protection to virtually eliminate annoying amplifier shut-down events. Should any XDv2-Series amplifier ever overheat, its intelligent, unregulated power supply reacts by limiting available peak voltage until the amplifier returns to a safe temperature range. Likewise, if an impedance lower than optimal for the amplifier is present at the outputs, the XDv2 amplifier will roll back peak voltage to protect itself without shutting down.

Differential-Balanced Inputs: The XD400/4v2 features differential-balanced input architecture to effectively control noise and ensure compatibility with a wide variety of source units, including many OEM systems. Without resorting to line output converters, you can directly connect most OEM source units to the amplifier without creating any noise or compatibility issues. Unlike conventional single-ended inputs, the differential-balanced design does not connect one side of the audio signal to chassis ground. This eliminates any voltage sensitivity between one input terminal and ground and greatly reduces the incidence of alternator whine in a typical car audio installation.

Note: You will need a Speaker Wire to RCA adapter (sold separately) for each pair of channels to connect this amplifier to your head unit via speaker level.

Protection Circuitry With Status Indicator Lights: There is a single multi-color LED on the top panel of the amplifier to indicate the amplifier's operating status.

  • Flashing Green: When the LED is flashing green, the amplifier is powering up and audio output is muted.
  • Constant Green: This LED lights green to indicate that the amplifier is turned on and operating normally.
  • Constant Red: This Red LED lights to indicate that the amplifier has exceeded its safe operating temperature, putting the amplifier into a self-protection mode, which reduces the power output of the amplifier. The red light will shut off and the amplifier will return to normal, full-power operating mode if the heat sink temperature drops back to a safe level.
  • Constant Amber (Yellow): The Amber (Yellow) LED light indicates that an over-current condition has occurred and is accompanied by a muting of the amplifier's output. Over-current condition can be caused by a speaker impedance lower than the optimum load impedance range for the amplifier or a short-circuit in the speaker wiring.
  • LED Off: The only condition that will shut down an undamaged XD400/4v2 completely is if battery voltage or remote turn-on voltage drops below 10 Volts. The amplifier will turn back on when voltage climbs back above 11 Volts.

Cooling System: The outer shell of the JL Audio amplifier is designed to remove heat from the amplifier circuitry. For optimum cooling performance, this outer shell should be exposed to as large a volume of air as possible.  Enclosing the amplifier in a small, poorly ventilated chamber can lead to excessive heat build-up and degraded performance.


Control Panel Cover: The XD400/4v2 features a brushed aluminum Control Panel Security Cover which protects and hides the amplifier's controls. When installed, the cover ensures that the amplifier's settings are not accidentally changed while creating a clean aesthetic look for the amplifier and your installation. The control panel security cover is pre-installed at the factory and must be temporarily removed to access the amplifier's controls. The security cover is secured by two 2.5mm hex-head screws.

Simplified Gain Setting: This XDv2 Series amplifier makes setting the gain level of the amp via the input sensitivity control very simple. All you need is Digital AC Voltmeter and a CD Test Disc with a sine-wave test-tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofers, 1 kHz for a midrange application). Each pair of channels has a separate Input Sensitivity control.

Flexible Input Section And Active Crossover Network: The XD400/4v2 amplifier provides a flexible input section and a comprehensive crossover network to fine tune your system effectively and accurately. This 4-channel amplifier is divided into two separate pairs of channels, each with their own crossover:

  • Filter: The front and rear channels are equipped with a 12 dB/octave Butterworth filter which can be configured as a low-pass (LP) or high-pass (HP) filter, or defeated (OFF). You can set the Filter Mode via a three-way switch.
  • Filter Frequency: The filter frequency can be selected using the rotary control. The control has forty detented positions for selecting the precise frequency you desire. There are markings at 50Hz, 60Hz, 80Hz, 120Hz, 200Hz, and 500Hz, plus there is a chart in the Owner's Manual with the exact cutoff frequency for each detent. You'll need a small screwdriver (not included) to set the frequency.

Turn-on Options: The Turn-on Mode Switch lets you choose the method for turning the amplifier on and off:

  • +12V Remote Turn-on Lead: The preferred method for turning the amplifier on and off is by running a turn-on lead from the source unit and connecting it to the Remote terminal. When +12V is present at the terminal, the amplifier will turn on. When the +12V is turned off, the amplifier will shut off. The set screw connector on the Remote terminal will accept 18 AWG to 12 AWG wire.
  • DC Offset-Sensing: The amplifier will turn on and off when the presence of a very small DC signal (or offset) is detected on the amp's RCA left channel input. The amplifier will turn off when this DC Offset is no longer present. This method is designed for high-level (speaker-level) input signals, not for low-level (line-level) signals.
  • Signal-Sensing: The amplifier will turn on and off by detecting the presence of a full-range audio signal at the left-channel input. The amp will turn off approximately 30 seconds after the audio signal is no longer detected. This method is designed for use with high-level (speaker-level) input signals and not for low-level (preamp level) signals.
Note: When the DC Offset or Signal Sensing turn-on methods are being used, the amp's Remote terminal can be used as a remote turn-on output for other amplifiers or accessories in the system.

Additional Controls: In addition to the Input Sensitivity, Filter Mode/Frequency, and Turn-on Mode controls, the XD400/4v2 has the following controls under the control panel:

  • Preouts From: The pass-through preamp outputs can be configured two different ways:
    • 1&2: The preamp output delivers the same signal that is connected to the CH 1&2 inputs. This allows channels 3&4 to be faded without affecting the subwoofer level. If CH 1&2 is faded in this mode, the signal level of the preamp output will change accordingly.
    • Sum: The preamp output will deliver a summed Front/Rear stereo signal to a subwoofer amplifier, while permitting fading from the front to rear speaker systems from the source unit. No loss of signal occurs to the subwoofer amplifier when the system is faded to the front or rear by the head unit.
  • Remote Level Mode: You can assign the operation of the connected HD-RLC to one or both pairs of channels. This two-way switch lets you select ALL or 3&4.
  • Input Mode: The Input Mode switch lets you send four discrete channels into the amplifier, or use only two channels to feed all four amplifier channels. You can set the Input Mode to 4 CH or 2 CH.


Power/Ground/Turn-On Terminals: This JL Audio XDv2 amplifier features set screw clamp terminals for the power, ground, and remote turn-on connections. A 2.5mm hex-wrench is supplied for tightening or loosening the set screws.

  • Power and Ground: The amplifier's set screw clamp Power and Ground connections are designed to accept up to 4 AWG power wire. JL Audio recommends 8 AWG power and ground wire for this amp.
  • Remote Turn-On: The amplifier's set screw clamp turn-on lead will accept 18 to 12 AWG wire.
Note: The Amplifier is not equipped with a fuse. An external 40-amp AFS, AGU, or MAXI fuse must be installed on the power wire. If a wiring kit is used which includes a fuse with a value other than 40 amps, the original should be replaced with a 40-amp fuse.

Speaker Output Terminals: The JL Audio XD400/4v2 features four set screw clamp speaker terminals for an easy stereo connection. You can also bridge the amplifier by connecting a 4 ohm load to the CH1/CH3 positive and CH2/CH4 negative terminals. The terminals will accept 16 to 8 AWG speaker wire.

Preamp Inputs: The amplifier features two sets of differential-balanced RCA jack inputs with an Input Voltage switch. For preamp level signals, the switch should be set to LOW. For speaker level signals, the switch should be set to HIGH. The rotary Input Sensitivity gain control can be set the amp to the specific signal source that is feeding it. The amplifier's input voltage range is 200mV-2V (LOW) and 800mV-8V (HIGH).

Preamp Outputs: The XD400/4v2 incorporates a buffered pass-through preamp output section, so that additional amplifiers can be easily added to the system. The preamp output signal is not affected by the amp's Low-Pass Filter. If the Input Voltage switch is in the LOW position, the level of the Preouts matches the input signal strength. When the Input Voltage switch is in the HIGH position, the level of the input signal is attenuated -12dB to produce a line-level signal at the Preouts. You can select which channels feed the preamp outputs: 1&2 or Summed.

Remote Level Control: The amplifier features a standard RJ-14 telephone connector for adding the optional wired HD-RLC Remote Level Control (sold separately). The Remote Level Control lets you control the volume of the XD400/4v2 from the driver's seat.

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.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

4 channel amp with remote control of channels and clean JL power. What not to like? [ DAVID  Aug 21, 2018 ]
BC JL is the best [ ross  Feb 16, 2017 ]
Daisy in support helped me with this purchase. [ Samuel  Dec 24, 2016 ]
Heard good reviews about SQ on this amp. [ James  Jul 21, 2016 ]
This AMP has great RMS power into 4 channels, and can accommodate factory head unit low-power OR high power inputs. It is so configurable and has the ability to isolate the input to reduce noise. Amazing features, and I have owned JL audio in the past - awesome sound. Can select bandpass, and send pre-outs to my sub based on SUMMED 4 chanel inputs so that Sub is not affected by fade... A bit more than some, but well worth it for the quality and features. [ R  Feb 02, 2016 ]
I was recommended this amp by a local brick and mortar audio retailer, but noticed it was on sale through Crutchfield, and even cheaper still with a scratch and dent unit. The advisors answered all my questions and made my decision that much more easier. JL Audio has had a solid reputation for the 20 plus years that I've been buying audio equipment. This amp fit the bill for my particular needs, powering component door speakers in an extended cab truck and running a small sub. [ CASEY  Jan 29, 2016 ]

4 questions already asked

For more personalized assistance relating to your specific vehicle, please contact an Advisor directly by phone (888.955.6000) or online chat. They can help you determine if the JL Audio XD400/4v2 is the right amp for your installation; and if not, they can suggest a better alternative to suit your vehicle, system and/or budget. Thanks! [ Larry  Jun 18, 2018 ]  Staff
Yes this is a perfect amp for those speakers. Paired theses with a jl w7 12 inch sub and my neighbors hate me [ Christina  Mar 28, 2015 ]
Thanks for your question. For information on selecting the best amp for your subs I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences between the amp models and help you make the best choice for your system. [ Krissy  Dec 10, 2014 ]  Staff