So far so good!
Crutchfield customer from Phoenix, AZ on 2/8/2021
2017 Honda Civic SI
Great name and great amp. I have this amp running my new Focal setup in my 10th gen Si. To be exact, I have the Focal Performance PS 165FX fronts and ICU 100's in the rear deck rounded out with a RE 12. Only around 5 hours on these speakers/amp so far, getting better every time I get in. I don't suspect I will have ANY issues with this amp, reason I went with JL Audio. Clean and crisp power is all I have heard so far. Hopefully many years to come!
Pros: Small footprint and large sound
Cons: Pricier than other amps
0 of 0 found this helpful
JL Audio RD400/4
Crutchfield customer from Hanover, NH on 12/22/2020
2020 Honda CRV EX
Perfect match for Alpine 6.5 Rs. Life is much easier when the consultants ask the right questions , it makes them truly helpful .
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Cons: None
1 of 1 found this helpful
Look no further!!
Kevin from Lamoni, IA on 9/13/2020
2003 Kia Spectra
Was having bad luck with a Kenwood Excelon 4 channel amplifier So I went and got this one. This thing blows the Kenwood out of the water! I really can't describe how much better it really is and the clipping indicator is spot on. I tested it with my O-scope and it 100% passed for me. I will recommend people buy this one and I'm also looking into buying one of JL Audio's mono amps for subwoofer!
Pros: does 100% everything that it says in description.
Cons: none
1 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Ottumwa, IA on 9/3/2020
2011 Nissan Maxima
Looks good does what he says easy to set up
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0 of 0 found this helpful
JL Audio RD400/4
Crutchfield customer from Jeffersonville, IN on 8/23/2020
2014 Lincoln MKS
I purchased this RD400/4 amplifier to run my 2 pairs of C2570X 5X7's. I also purchased RD1500/1 to run my subwoofer. Unfortunately I can't find the Q Class L7 15 inch 2 ohm sub that I want for my project. These amplifier and speakers were packed exceptionally well. I have purchased JL Audio amplifier before. I am not worried about the quality or performance of these amps. Once I can get my sub I will do another review.
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0 of 2 found this helpful
I like it
Lael from Mount Olive, AL on 6/4/2020
Excellent amp so far. Vast improvement from the JL JX400 I had prior. Pushes my Infinity Primus line up with ease and clarity.
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2 of 2 found this helpful
JL Audio RD400/4
Crutchfield customer from Berkeley, CA on 5/21/2020
1 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Schertz, TX on 5/11/2020
2013 Toyota Tacoma
Nice upgrade over the Kicker that it replaced. Adjustment options are straightforward.
Pros: Easy set up. Sounds good.
Cons: Had to go another website to download test tones.
0 of 0 found this helpful
Great Amp
Crutchfield customer from Mukwonago, WI on 5/5/2020
2012 Toyota FJ Cruiser
So far it's a great amp more then fit my needs as an addition to my FJ audio upgrade project. Always been a fan of JL and have not installed in years. Getting back in the game with this amp has been fun. Plenty of adjustments and the clipping adjustment is great idea. Ultimately you end up adjusting it to your system but it's a great reference
Pros: Great adjustability
Cons: Non for me
0 of 0 found this helpful
Sounds awesome
Juan from Brea, CA on 5/3/2020
Never had it, looking forward to owning it soon. Thanks.
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0 of 10 found this helpful
JL Audio RD400/4
Crutchfield customer from Baton Rouge, LA on 4/28/2020
2004 Dodge Ram 1500
Great amp! Easy to set inputs/gains, sounds great and looks good!
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1 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Selma, TX on 4/28/2020
2007 Porsche Cayman
Awesome amp. Plenty of power and no added noise. Love it!!
Pros: Great price and excellent quality
Cons: None
1 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Asheville, NC on 4/20/2020
Very good amp, it's versatile....small size, great punch, easy install, with clear sound. A little more money than compared to other amps in this wattage range, but money well spent. Great addition to my stock head unit.
Pros: Compact size. Accepts low-level and high-level signals from factory head unit.
Cons: None.
1 of 1 found this helpful
good sound
audio junkie from Eugene, OR on 4/16/2020
really good amp. sound good, has good power. thats all pretty impressive however alternator whine started happening. cleaned and checked all connections for chassis and power. comes down to would not filter out the noise. replaced with alternate d class amp same location and connections. problem solved. that may not happen for everyone. sound quality is very good
Pros: small, efficient, powerful
Cons: alternator whine.
2 of 3 found this helpful
JL Audio RD400/4
Crutchfield customer from Ontario, CA on 3/5/2020
Unbelievably awesome. This thing did a miracle for me
Pros: No wire cutting
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1 of 2 found this helpful
Sweet music
Crutchfield customer from Lake Jackson, TX on 1/30/2020
What a great amp, it's does an excellent job of cleaning up the signal and producing crystal clear sound. A little more money than other units in this watt range, but money well spent.
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2 of 2 found this helpful
After All
Craig from Oak Grove, MO on 1/22/2020
After all it is JL Audio. Small size, no noise, great punch, easy install, fantastic sound...after all, it IS JL Audio.
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3 of 4 found this helpful
JL Audio RD400/4
Crutchfield customer from Scottsville, KY on 1/14/2020
Perfect choice for amplifying my stock head unit. Super easy install. Love it!
Pros: Clean sound, power to spare
Cons: None
0 of 0 found this helpful
JL Audio RD400/4
Crutchfield Customer 4 Life from USA on 11/9/2019
Small/compact, clean power!!! Smart amplifier that perfectly configures your vehicles audio to be distortion free!!! Protects and ensures that all your components will last during the life of your car!!!
Pros: This Amplifier eliminates the need for Line Output Converters (LOCs) in most installation scenarios. Amplifierc accepts low-level and high-level signals from a variety of factory head unit outputs and amplifiers, including single ended "ground referenced" sources, Balanced or Unbalanced "Bridged or BTL" sources. . Daisy chain multiple amplifiers with ease.
Cons: No bass knob. A bass knob does put more stress on an amplifier. JL AUDIO ensures all audio output is always always flawless. You must configure/tune the bass on the amplifier itself and then rely on your factory head unit or aftermarket head unit to make specific adjustments on your song selection. This amplifier does add the bass you need by increasing the rms power from the head unit. A bass knob is not needed with this amplifier. .
6 of 10 found this helpful
JL continues to inpress
Crutchfield customer from Hampton, VA on 10/6/2019
This amp has plenty of power for what I need. The size of it and how clean my speakers sound compared to a cheaper amp I had makes a huge difference. I'm using Hertz Mille 3-way comments in the front and Hertz Mille 6.5" coax in the rear. This amp makes them scream. The build quality is something that can be expected from JL but you can also tell a lot of thought went into it. Nothing on it feels cheap.
Pros: Small foot print, solid build, plenty of power. Well worth the money.
Cons: None that I can think of.
3 of 3 found this helpful
JL Audio RD400/4
Crutchfield customer from Anchorage, AK on 10/4/2019
0 of 0 found this helpful
JL Audio RD400/4
Crutchfield customer from Austin, TX on 8/14/2019
1 of 2 found this helpful
JL Audio RD400/4
John from Somerset, NJ on 7/21/2019
Lot of power for a small amplifier excellent sound quality for my Interiors my entire sound system JL Audio
Pros: Never go wrong with Jl
Cons: None
0 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Covina, CA on 7/16/2019
Great product. Installation was simple and speakers sound great.
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0 of 0 found this helpful
JL Audio RD400/4
Crutchfield customer from Texas City, TX on 6/10/2019
Awesome sound way better than expected
Pros: Perfect for highs and mids
Cons: None
2 of 2 found this helpful
Good solid amp
franc23 from Northborough, MA on 12/7/2018
Good product. First real amp. Controls are easily accessible though best not to play with it much once set. Came away impressed. Tough to fit in a truck, ended up sealing the vent on the passenger side and this went below that seat.
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2 of 2 found this helpful
JL Audio RD400/4
Crutchfield customer from Puyallup, WA on 12/3/2018
Sounds great liked all connections on one side mounted well also
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1 of 1 found this helpful
JL Audio RD400/4
Crutchfield customer from Mesa, AZ on 11/9/2018
Great product lots of adjustments Fits in small spaces
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0 of 0 found this helpful
JL Audio RD400/4
Joe from St Augustine, FL on 9/9/2018
0 of 2 found this helpful
JL Audio RD400/4
Crutchfield customer from Lewisville, TX on 8/29/2018
0 of 2 found this helpful
Great 4 channel amp
FrankyG from Bellflower, CA on 8/11/2018
Awesome 4 channel amp. Worth every dollar. Night and day from previous amp. JL audio might be a little more pricey than other audio equipment but you pay for what you get.
Pros: Compact and packs a punch. More than enough power for my set up
Cons: None
5 of 5 found this helpful
JL Audio RD400/4
Crutchfield customer from Tucson, AZ on 8/7/2018
product is as described and works great. I have had no issues at the time of this review. I will add more info if I run into any problems.
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0 of 1 found this helpful
Easy Install
Phil from Wilmington, DE on 6/28/2018
I used this to replace a dead Infinity Reference amp. The install was easy since I had all the wires run already. The LED clipping lights and the test tone download from the JL website made setting levels easy. The sound is just a bit cleaner than the old amp and it doesn't get hot to the touch even though it is half the size.
Pros: Small and cool to the touch Easy Install
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4 of 4 found this helpful
Woke up my system
George from Richmond, VA on 6/21/2018
Added this amp with Alpine speakers. Really woke up my system. Very happy how it sounds.
Pros: Fantastic clean sound. Look great mounted too.
Cons: None
1 of 1 found this helpful
JL Audio RD400/4
Kevin from Upper Marlboro, MD on 6/11/2018
Great product Easy to install and good sound Stays cool
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1 of 2 found this helpful
JL Audio RD400/4
VERONICA from Fairfield, AL on 5/31/2018
Love the sound.....no other competitors comes close.... .Crutchfield & JL Audio y'all got people hating on me ....lol
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2 of 5 found this helpful
All you need for mids-highs
Rick from Elk Grove, CA on 4/24/2018
Awesome amplifier, lots of power. Plenty of parameter settings available. Simple to install; I love the blue LED light! Most importantly it has plenty of power to drive my 6.5" mids. Thanks Sam at Crutchfield for recommending this amp to me!
Pros: Plenty of power, good price point
Cons: None
3 of 3 found this helpful
JL Audio RD400/4
Crutchfield customer from Louisville, KY on 4/16/2018
Good amp very easy to install the crossover adjustment are great delivers good power when needed doesn't over heat
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2 of 3 found this helpful
JL Audio RD400/4
Theodore from Midland, MI on 12/8/2017
No complaints, Easy setup and sound clean. Recommended in this price range.
Pros: Gain adjustment.
Cons: None found
0 of 2 found this helpful
Takes the guess out of work.
Dave from Cowen, WV on 11/18/2017
I picked this up to replace a physically larger Infinity Reference 704A. Everything is mounted to the rear wall of my F150 Supercab and needed that extra space. The install was easy, the output clean, and it was no sweat dialing it in. Not that anyone will ever see mine, but it's nice to know that it looks as good as it sounds. The only downside was that I was missing the mounting screws. Fortunately, I had some from a previous amp that I pressed into service and didn't have to resort to using assorted wood screws that were laying in a drawer in my workbench.
Pros: Small footprint and easy to dial in.
Cons: No mounting hardware? What gives?
3 of 3 found this helpful
Great for the price
Mark from MINNEAPOLIS, MN on 9/3/2017
I've had this amp for a few weeks running C3's on the front channels and C2's on the rear for fill. Having previously ran the Slash V2 and V3 series 4 channels as well as the J2 Series 4 channel, this amp definitely isn't the BEST in the JL line. I've never seen the HD series in person so I can't comment on that, but I would say the RD is definitely just below the Slash series. Good amp for the price, very compact and efficient, with decent settings and filters for the price. I would recommend for anyone who wants to break away from the entry level amps like Kicker and Pioneer. You definitely won't regret the investment!
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12 of 13 found this helpful
JL Audio RD400/4
Crutchfield customer from Jackson Heights, NY on 6/20/2017
I love it easy set up and it sounds great! Going deaf already!!!
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2 of 6 found this helpful
JL Audio RD400/4
Crutchfield customer from Clearfield, Ut on 6/1/2017
Very happy with this product. The Jl audio Rd 400/4 is a awesome product. I'm powering jbl 6.5 components and jbl 6x9 with a pioneer head unit. Very clean sound.
Pros: Great price High end construction Power 75x4 @ 4 ohms Small size
Cons: Can not find any
4 of 4 found this helpful
JL Audio RD400/4
Glenn from Union, MO on 4/6/2017
Awesome, need to use the HP filter for regular speakers and tune the filter some or it will eat em' up with bass also used this with the little Kenwood (2 channels) one for 6 channels total. Recommend Rockford Speakers
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1 of 5 found this helpful
Good quality
Bobby from Birdsboro. PA on 4/5/2017
Great sound and made of high quality material as expected. Service was great as always one of their fellow customer service reps helped me pick the best option in my price range.
Pros: Easy to set up and small size
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4 of 5 found this helpful
JL Audio RD400/4
LUAN h from Atlanta, ga on 1/16/2017
Fit nicely under the seat and it does what it suppose to
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2 of 4 found this helpful
JL Audio RD400/4
Crutchfield customer from FORESTVILLE, CA on 10/17/2016
I PURCHASED THIS AMPLIFIER TO REPLACE AN OLDER SOUND STREAM AMPLIFIER. INSTALLATION AND TUNING WAS EASY,.MOST IMPORTANTLY IT SOUNDS GREAT.
Pros: SOUNDS GREAT SMALL IN SIZE
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4 of 5 found this helpful
JL Audio RD400/4
CBR Bob from Hamilton, NJ on 10/14/2016
Smooth, easy installation. Replacing an old amp... Easy to adjust and set up. Good sound as expected.
Pros: Runs cool
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3 of 4 found this helpful
