Kenwood made their reputation building car amplifiers that offer no-nonsense reliability and superior sound quality. The compact KAC-9104D mono amplifier features a rugged cast-aluminum chassis 30% smaller than its predecessor, yet it'll still punch out up to 900 watts RMS to your subwoofers without straining your car's electrical system.

A built-in low-pass filter adjusts amplifier output so you'll get the best sound possible from your subwoofer/box combo, while the subsonic filter eliminates inaudible, ultra-low bass that can detract from your sub's performance. You can dial in up to 18 dB of bass boost if you want to fatten up the sound.

The front-mounted controls allow you to tweak the sound easily, and convenient front-side connections make setup a snap. Signal sensing turn-on and speaker-level inputs allow these amps to hook up to factory radios that don't have preamp level outputs.

Product Highlights:

  • mono subwoofer amplifier
  • 500 watts RMS x 1 at 4 ohms (900 watts x 1 at 2 ohms)
  • 1-ohm stable (output regulated to 900 watts)
  • CEA-2006 compliant
  • variable low-pass filter (50-200 Hz at 24 dB per octave)
  • bass boost (0-18 dB at 40 Hz )
  • subsonic filter (15/25 Hz, 18 dB/octave )
  • Class D design
  • speaker-level inputs with signal sensing turn-on
  • preamp-level inputs and outputs
  • fuse rating: 30A x 2
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 13-11/16"W x 2-3/8"H x 9-5/16"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.

Kenwood KAC-9104D Reviews

Average Customer Review:

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Kenwood KAC-9104D

Written By Anonymous, Anaheim, CA on Tuesday, February 28, 2012

Hits hard, sounds great. Well worth the money. Great budget amp. I had this before I got my Rockford amp and loved it!

Pros: Budget amp

Cons: Killed my alternator lol


Written By davidsw, tulsa,ok on Sunday, May 08, 2011

Crutchfield Customer Review (What's this?)

I see all the great reviews and maybe I baught a junk one sense it was refurbished.I will say this think had loads of power,I have it hooked to a fosgate ps3 12" and when it hits a really low note ir just play it loud for a period of about 6 to 10minuets it pops the 30 amp fuse so I havent had the chance to turn this thing up or tune it because it keeps popen fuses but what i have herd is some real thunpin base but not for I eather got a bad one or this thing is just a piece of junck......

[Editor's Note: I apologize for the problems you have experienced with this unit. Our Technical Department will be in contact with you to set up a return/exchange.]

Best budget mono subwoofer amplifier

Written By JM, Orange County, CA on Friday, March 25, 2011

True 900Watts RMS @ 2ohms and a liitle more @ 1ohm! It shakes my 2pcs 12" subwoofer so hard i won the local SPL competition with my 148dB in the 1000W and under category. I had an engineer open the amp and to his surprise the power supply inside inverts the 12V/14.4V to over 70V unlike most more expensive amplifiers at 40V to 50V only. So at 70V squared divide by impedance at 2ohms, resulting power is over 2450 watts and an efficiency of around 60 percent, actual power is at 1470Watts. But kenwood claimed that they regulated the power to just around 900 to 1000W, so we really know this amp is capable for more serious power!

Most power for the money. Period!

Written By Travis, Independence, MO on Thursday, August 19, 2010

I have owned many amps over the years from RF, MTX, and so on. All were great amps but I will have to say I was most surprised by this Kenwood. First thoughts after first picking up the amp is no way this is a 900 watt amp because it doesn't weigh very much at all compared to other amps I have owned. The RF P3001 (300 Watt) I was replacing weighed twice as much. After installing it with 4 gauge power and ground wire with a 1 farad cap on two Kicker 12" L5's I was totally amazed! This amp puts down some power and that aint no joke! Only down fall Is no remote bass knob but if you get it dialed in you really don't need it. You WILL NOT be disappointed in the power this Kenwood will deliver I promise!

Solid Amp

Written By Hoogie, Washington State on Tuesday, March 23, 2010

I had this hooked up to 2 alpine type r 12's at a 1ohm load and it hit so hard I removed one
because I was losing my hearing. I don't know why people have a problem with the amp
cutting out I have no problems whatsoever. True it is only putting out 644 watts RMS at 14.4
volts. I also have a 5 farad capacitor in use along with my setup maybe that helps, it helped
my lights stop dimming. Before the capacitor when the bass hit hard at high levels it was
actually shutting off my cd player, or making it skip.


Written By babajan, SAN FERNANDO, CA on Sunday, March 21, 2010


Good amp, good price

Written By Mike, Tampa, FL on Wednesday, March 03, 2010

Crutchfield Customer Review (What's this?)

I purchased this amp right before it was discontinued; and I'm glad that I caught it. I
bought it to power two Kicker Comp VR 07CVR102 2-ohm dual voice coil subs, and to
help spare my electrical system, I bought a Tsunami Lite Wave 1.2 farad Capacitor. I
haven't even adjusted the amp, and I have the bass on my my Sony cd reciever on 0 and
all I can say is that This amp is doing it's job! It has my subs rattling my trunk and my
rear view mirror bouncing. I don't see myself having any problems with it, and if I did
crutchfield would surely exchange it me.

I would definately recomend this amp to anyone who can get their hands on it!!!!!!!!!!!


Written By scuba steve, Onida SD on Monday, October 19, 2009

This is a really nice amp i have it running a single kenwood excelon KFC-1222D sub and it does awesome. A must for any kenwood fan.

1 ohm great! you get what you payed for and more possibly

Written By cheezit101, satellite beach florida on Saturday, September 05, 2009

Allright. I bought this amp about 1 month ago. Wicked cheap price. Brand new in the box.. Opened it up and stoked to see how beautifull and sleek it looks. Anxious to see it perform i brought it to my car immediatly and spent the rest of the day fiddling with it.. / the last month. heres what ive experienced so far.

First off my wiring from battery + terminal is a 5 gauge scosche wire with a 100 a fuse in it. Goes to my trunk, then is split by a block into a 8 gauge wire.

The ground is a 8 gauge i put to some metal with a screw in it behind my back seats.. somewhere that connects to bare metal / the whole car. ( i think). I used to have it grounded to another bolt under the carpet in the trunk and it had alot of noise when on low volume.. so i changed it. less noise now.

Speakers i used was a 12 inch dvc 4 ohm 500 rms JVC Warren G sub.

Then a duel set of 12 inch dvc 4 ohm 400 rms sub.

Kenwood KAC-9104D

Written By john19055, Greenville,TX on Wednesday, August 26, 2009

The first thing that should give it away is that it just has a 60 amp fuse on it ,plus it says it only draws 55 amps. 14.4v x55amps =792 watts ,plus you usally don't get the full 14.4v back to the amp ,usally just around 13.6v if you have heavy gauge wire .13.6 v x 55 amps = 748watts. A 105 amp alternator is plenty big enough as long as your alternator is working proper.I had a 100 amp alternator with a good deep cycle battery and had my alternator wires upgraded to 4 gauge plus my chasis ground.I had 0 gauge going to my Rockfordfosgate RF-X7 which put out a true 1750 watts and never had a amp cut off and never had no problems with my 100 amp alternator.I was just dissappointed in this amp.

Very Powerful Amp

Written By Burninrock24, Bloomington, MN on Sunday, June 28, 2009

This Amp is very straight-forward and powerful. I have it wired to 2
Kenwood 400 watt RMS subs at 2ohms and a pioneer head unit via. patch

I couldn't believe the sound that this amp was producing, on 0 bass boost
(on both the reviver and the amp) it was already overpowering my music.
The low pass filter is good if you have subwoofers that have a low Xmax.
and the line level inputs are great for adding bass to a factory system.

The installation was incredibly easy, the hardest part was hiding the wires
overall I am very very pleased with this purchase. I would definately
recommend this amplifier.

NOTE:: As far as the cutting out problem people are experiencing; I have
not experienced this since the problem is caused from a lack of power from
the car. I have a 130 Amp alternator on my Explorer so I don't have this

Best amp

Written By Michael, Lynchburg, va on Tuesday, May 19, 2009

Out of all the amps I have seen and heard the best one is this one! Like the other review said it does cut of on very long bass notes but it is not caused by over powering! The reason why is because if you start your vehicle and look at the voltage meeter while the bass is pumpin long and hard the voltage will drop pretty darn good and the amp will cut off! The reason for this is that your amp is not getting the power it needs to process the long bass! A capacitor will help a little but will not resolve the issue! The factory altenator is not made to power a powerful amp. So I bought an aftermarket atenator that pushes 160 amps instead of the factory 105 amps! Doing this will resolve the issue! I have two 12" kicker cvr122 hooked up at 2 ohms and it hits very hard! Hard enuf to give you a through back massage and makes you hold your breath! Over all this is a monster of an amp and is well worth the price!

Kenwood 9104D

Written By Collin, Arizonya on Saturday, April 11, 2009

I initially hooked it up to one KFC-W3011 and it hit HARD! My logic was then to add another KFC-W3011 woofer and it would hit twice as hard! My logic was flawed.. I can barely notice a difference between one 12 and two 12s. I cannot get the speakers to distort no matter how much I turn up the volume, bass boost, gain, everything.. I think I need some 0 gauge wire and a capacitor to really make this system hit but as of now I wish I would have just stuck with one 12 and this amp. It keeps turning off during lengthy bass notes too which makes me a little sad inside. I don't think it's overheating as when this happens it is not even hot to the touch. Oh well, for the price I paid, I'm satisfied.

Best Monoblock ever

Written By Jacek, Little River SC on Monday, March 02, 2009

Crutchfield Customer Review (What's this?)

Ok, so at first I had the kac8104D amp pushing my 2 12w1v2 jl's that was very impressive. Then I bought this amp and i am very impressed with it, i also went with old school 2 12w3 at 4 ohm and oh my god shook my rearview mirror off. I like this amp...

Not true power, but an Ok buy.

Written By Audible Insanity, Louisiana on Wednesday, September 17, 2008

This is an ok little amp, but much better could be had for the $.
It is priced roughly the same as other 600-700wrms amps on the market for a reason...THIS AMP IS NOT A TRUE 900WRMS.

This amp has been tested at 644wrms @ 14.4v into 2ohm.

Remember this before buying.
If you are looking for 600-700wrms, this will be fine. But only produces around 72% of rated power (as per Car Audio Magazine test).

This amp is 1ohm stable, but Kenwood advertises the amp as don't expect much more power at 1ohm.

Kenwood KAC-9104D

Written By bordr77, Brighton, CO on Tuesday, September 16, 2008

Im not very impressed with this amp, i see that alot of the people that are impressed with it are powering something at 4 ohms. As for me i am trying to push a MTX 9500 at 2ohms with the hope that there would be 900 watts rms powering my 1000 watt rms sub. After reading a review on this amp i have come to find out that if it is 4ohms you looking to run that your good to have your stated 500 watts but as for 2 ohms if i dont mistake the power was only said to be around 560 or so RMS and when turning this amp up and seeing how my speaker moves and the sound that it delivers I am sure it still has alot more in store. I guess all i can say is that i got what i paid for, I should have done some more research.

Just got it, its nice

Written By Peter, Amherst, MA on Saturday, September 13, 2008

This was my first sub/ amp installation and they sound great. I have 2 10" 500w RMS subs wired at 2ohms to the amp and the bass is amazing. I'm still tweaking the controls to get the best sound, but the bass boost and sensitivity are at a pretty low level on the amp and the speakers are really loud already. The amp has not gotten hot as of yet. It's just nice.

Kenwood Krazy

Written By PrynceAl, Duval Da' Bang' Em on Wednesday, August 06, 2008

I went ahead and outfitted the Honda w/ KDCX492 head unit, 1- KFCW3011 12", the KAC 9104D and a 2Farad capacitor. I am trying my best to blow the system but it ain possible right now the 12" sub paired with the 9104 amp is krazy...I have this amp at 0 gain running 4 ohms with the head unit's subwoofer level set to +9...I sware its the hardest hittin $100 sub I have ever heard before; its real stupid and its a lil more than what I bargained for. But don't forget its hittin like that b-cuz of this amp, all I need is 4 ohms if it gets any louder than this I don't even wanna hear it. The 9104D is krazy yal gotta check it out to beleive it...O yea don't forget the Dynamat you'll need it to keep the bass clean...and get a cap, this amp requires power but it delivers everything right back to you!

Kenwood should change their name to "Got Wood"?!!!!!

Nice Amp At 4 Ohms

Written By JT1, Michigan on Tuesday, May 27, 2008

This is the first amp that I have bought. After I got it, I hooked it up to a single Alpine SWR-1222D Subwoofer wired at 4 ohms. I was very impressed. It matched up perfectly with the power rating of the Alpine Type R. I then purchased an additional Alpine SWR-1222D and hooked it up the other day. It was very loud. However, if I turned my volume up on my Pioneer receiver past 10 (From 0 to 62) it will cut out for a period of time. I checked the wiring and all was well. I don't know if a capacitor will fix the problem. A plus to this amp is the cooling fan. So far it has not gotten really hot on me. If you are looking for an amp that puts out 500 RMS watts at 4 ohms, this amp is great. If you want it for 2 ohms, I would look for a different amp. If the problem of it cutting out is fixed this amp would be an easy five.

Lawd have mercy

Written By Rod, Beaufort, SC on Wednesday, April 16, 2008

This Amp right here is the best amp I've bought in a while. I was kind of unsure of this amp at first but when I hooked it up I was surprised. I have this amp hooked up to a kenwood Dvd player unit and one 12" Kicker comp vr. in a sealed box and it plays clear and and has deep bass. I will not sleep on Kenwood again...

Hands-on research

What's in the box?

Download owner's manual

  • Mono-channel amplifier with two 30A fuses inserted in chassis
  • 8" Speaker-level input harness
  • 4 Self-tapping screws (4mm diameter x 16mm)
  • Rubber terminal cover
  • Allen wrench
  • Instruction Manual
  • Warranty card

Product Research



CEA 2006 Compliant: The KAC-9104's power ratings are measured according to the strict standards dictated by the Consumer Electronics Association (CEA). These standards allow you to accurately compare the rated power output of all CEA 2006-compliant amplifiers, even if they come from different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging.

1-Ohm Stable: The amp is capable of withstanding a low impedance of 1 ohms. This gives you more flexibility in connecting multiple speakers. For example, you can connect two 2-ohm speakers in parallel, or four 4-ohm speakers in parallel. When a 1-ohm load is connected to the amplifier, the power output is 900 watts or greater.

Speaker Level Input: The KAC-9104 comes with a two channel speaker level input harness. Once you splice the speaker wires from the receiver to the harness, you have plug-in convenience to the amplifier. This feature makes it easier to add an amplifier to a factory radio or to a receiver with no preamp outputs. The maximum power output from the source receiver can be no more than 40 watts.

Signal-sensing Turn-On Circuitry: When the speaker-level input is used, it is not necessary to connect the power control wire (turn-on lead). The amplifier senses the signal from the speaker-level input and turns the amplifier power on automatically. Shortly after no signal is detected, the amplifier will automatically shut itself off.

Low Pass Filter: The amplifier has a low pass filter, continuously variable from 50 Hz to 200 Hz, with a slope of 24db per octave. The filter is always on--there is no switch to turn the LPF off.

Bass Boost: You can apply a bass boost of up to +18dB at 40Hz. The rotary control is located on the front of the amplifier.

Infrasonic Filter: You can apply an infrasonic filter (also called a subsonic filter) to eliminate very low frequencies that are difficult to reproduce, rob amplifier power, increase distortion, and can damage speakers. The 3-way switch allows you to choose a cutoff frequency 15 Hz, 25 Hz, or Off (no filtering). The infrasonic filter has a slope of 18dB per octave.

Phase Switch: This amplifier is equipped with a 2-way phase switch. You can choose 0° (normal phase) or 180° (reverse phase), whichever position results in stronger performance for the subwoofer.

Protection circuitry: The amplifier features protection circuits that will turn the amp off in case of the following events:

  • Speaker output contacts ground
  • Speaker wire short-circuits
  • Unit malfunctions and DC is sent to speaker output
  • Internal temperature is too high
  • Loss of ground of head unit or amp

Fan Cooled: The KAC-9104 is equipped with two, rear panel-mounted cooling fans. One fan acts as an intake while the other serves as an exhaust to create a current of cooling air flowing through the inside of the amplifier.


Front Panel:

  • Bass Boost Rotary Control: 0-18dB
  • LPF Frequency Rotary Control: 50-200 Hz
  • Input Sensitivity Rotary Control: 200 mV-5V
  • 3-Way Infrasonic Filter Switch: Off-15Hz-25Hz
  • Phase Switch: 0° or 180°


Front Panel:

  • Fuse: 2 x 30 amps
  • Battery: Screw terminal (accepts up to 4 gauge wire)
  • Ground: Screw terminal (accepts up to 4 gauge wire)
  • Power Control (Remote Turn-on): Screw terminal (accepts up to 8 gauge wire)
  • Speaker Outputs: Screw terminals (accepts up to 8 gauge wire)
  • Line In: 1 pair RCA inputs
  • Line Out: 1 pair RCA outputs
  • Speaker-level input: Multi-pin input for use with included speaker level input harness

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.