Review: Harman Kardon HK990 Amplifier

Category: Amplifiers

It's really great to have an amp driving the AR9's again that doubles down on power. When the 9's were new, I biamped them with a pair of high current amps which doubled down, but time eventually did what it does to all amplifiers, and since then I've had several pairs of amps which made the 9's sound dull and boring. Once I had 1000w per tower with a pair of high current amps which doubled down and even then the 9's fell flat--not in a good sense. I told myself that time was wearing down the 9's like it did the amps--that the crossovers were getting tired. Or maybe the loss I was experiencing was actually my youthful imagination. Maybe the 9's never were commanding speakers that could talk a throaty, articulate musical language except in my youthful imagination.

Now with the HK990 I have the second amp that doubles down and the first one I don't need two of to drive the 9's, which are so full of sound again that they seem taller than their 4' ll 1/2" towers. They are even overful so that the transcients leap out of them; and they talk again. A friend who goes all the way back with the 9's said, "you'd never guess they aren't biamped". The HK990 is a beast which, inspite of the speakers' demands on this amplifier, runs only very, very warm--not hot.

The HK990 is an atypical integrated amp because the control amplifier is an active gain stage as stated in the owner's manual with its own voltage supply, and this integrated has the robust sound of separates where the preamp is an active gain stage. The preamp and power amp sections are not connected externally with bad-sounding U jumpers that need to be replaced with costly IC's. The switching is internal, and to access the power amp section you simply connect an external preamp to the "processor" input and select said source button on the front panel or remote. All six inputs have an adjustable "gain" feature so that switching from one source to another can be adjusted for consistency in output level. Set at zero gain, the power amp demonstrates only moderate gain. The more the gain in solid state amplification, the more the distortion; and the HK990 has the healthy sound of a power amp with only moderate gain. However, the preamp set at zero gain seems to have too much gain--seems to drive the power amp too hard, although when the HK990 drives higher impedence, less demanding speakers, the negative effects of this higher gain would diminish or maybe disappear. But when I trim the gain as much as possible, the sound quality is superb, and you can play with this feature to find the sweet spot. The gain feature significantly contributes to the amp's agility not only because it can eliminate irritating changes in sound level among various sources but also because it can be used to achieve optimum performance.

The HK990 left my highly regarded preamp and $400 DAC in the dust. I'll just say that's because of RLS 1V (Real-Time Linear Smoothing) because that's the easy, simplistic answer, although I'm sure there are plenty of other reasons, among them being that it's a bit of a hurdle to outperform the current $400 DAC's but surely not one too high for HK. RLS is a device that improves linearity at the point where the digital signal is converted to analogue and normally found only in high end professional equipment. Joe at HCGconsumergroup (Harman Kardon) has informed me that RLS is "not usually found in 'consumer' type products". Compared with my reference preamp and DAC, highs are open and smooth; bass is hard-hitting and thundrous, bass extention could hardly be improved.

Add to it the companion HD990 CD player with HRS Link and you can tweak the sound quality even more. HRS Link is an optional output on the CD player which locks onto the HK990's external clock to illiminate jitter using a cable that is included with the HD990 and that uses a standard RJ45 "network" connector. It is proprietary and is found only on Harman Kardon and Mark Levinson components per Joe. Using a reference digital cable which I connected to one of the HK990's inputs, I compared a digital input signal with and without HRS Link. First impression was that something was missing in the sound with HRS Link. The unconsious mind apparently processes jitter as a part of the music, and with HRS Link there is less quantity of sound so that sound minus jitter equals a purer sound. I found one review which claimed HRS Link to be definitely superior and one which could hear no difference in the several outputs of the HD990. These inconsistencies might be explained by the differences in other components--namely speakers and cable--or the room. Adaquate break-in is of course important as well previous to any critical listening. You will know when the HK990 has turned the corner on break-in. With this amp, break-in is dramatic.

The HK990 pretty much succeeds in being all things to all users. It features optional balanced imputs, optional "Direct Path" which minimizes switching in the analogue inputs, two sets of speaker terminals connected in parallel with a load warning, and a detachable power cord absent the ground termination but which accepts an EIAC power cord. It features optional tone controls, subwoofer outs with bass management, and room equalization as well. It includes an AD converter and phono section with MM and MC inputs. No USB port.

The HK990 does have one quirk that I haven't experienced with any other amp. When an appliance or a light switch is turned on, it cuts out for a split-second. Joe at HK said he's only heard of this issue from me and from his own experience with another model HK amp. His amp exhibited this behavior after he moved from one house to another. He resolved the issue by connecting the amp to another circuit, as I also did. Other possible solutions that come to mind are a dedicated circuit or a power conditioner with a storage capacitor, a feature absent in my entry level power conditioners. But the amp is so good that I would live with this anomaly.

The sound quality of the HK990 puts it deep into high end territory and makes it an extraordinary value. The extraneous components and features all in one box are just the bonus.

Lynne Arnett

CD's: Yellow Jackets, Time Squared; Flim & the BB's, Tricycle Gold; Don Dorsey, Beetovan or Bust; Yes, Fragile (MFSL); Dave Matthews Band, Crash; Norah Jones, Featuring..; Various Artists, Funky Organ; Dire Straits, Dire Straits; Holly Cole Trio, Don't Smoke in Bed; Johnny Cash, The Essential Johnny Cash. Cat Stevens, Cat Stevens Gold.

Associated gear
HD990 CD player
Acoustic Research AR9 (1978-1982)87db
SPL, 400w continuous
Anti-cable by Paul Speltz

Similar products
very interesting, thoughtful review which eschews the usual, purely subjective cliches and gets into the guts of the machine. the poster illuminates how things like internal switching, seperate voltage supplies for amp/pre, etc. really can make an integrated sound as good as equivalent separates.
i'd initially thought that a $2500 hk-branded two channel integrated was an ill-fated move, and was skeptical that it would really be significantly better than hk's very serviceable (and cheap)receivers like the hk3490. having finally heard it, however, it really is leagues above their mass market fare. when you consider that it has a high quality dac, massive power, phono, etc, it looks like quite a bargain as well.
good review. gets me to thinking about jettisoning some of my exisiting gear to buy one.
Loomisjohnson, Thanks for your comments. Lynne
Corrections: The amps which provided 1000w/tower did not double down and Beethovan needs an "h". Also I should have mentioned in the review that the sound of internal switching in the HK990 is the comforting sound of solenoids.
Just purchased one because all the reviews rave about how good of a deal this HK 990 really is. I agree. 5 Stars from me on this one. I downgraded from a bryston 4B SST 2 years old. I like it but had a hard time matching a preamp. Harman Kardon took out the guess work. Planning on buying the matching CD player. Great value and sounds every bit as good as the bryston stuff. Great Value for the Money here guys. Audiophile all my life. Wanted something simple back to basics.
I have a brand new HK990 and have read mostly great reviews on it's sonic performance. The biggest dissapointment I have is trying to use it's interface to select modes and adjustments. It's abosultely horrible to use. It's totally counter-intuitive. It's so typical of engineers who pack a lot of functionality into a device and then quickly pass through the design of the interface stage which would allow users to EASILY get to all this functionality.

Does anyone know where a tutorial exists from someone who has the scars of working through this interface?
Very informative review, thanks!

To the OP and others who've purchased the HK990, if you are willing to share the information I am curious as to what you paid for it. I've seen prices all over the map.
Harmon Kardon sells direct on line for $2000 including shipping. Thinking of getting one myself.
Just an FYI ... It looks like last Oct/Nov Harman Kardon sold several manufacturer refurbished HK990's on ebay for $999 with original factory warranty. There aren't any of those available on ebay at the moment, but if more pop up that's a pretty good deal.
Have been absent. Gz3827, glad the review was helpful. I think I paid $1875 for an open box from One Call in late 2011. Onecall had an open box recently and the price had gone up to $1900 or more. BTW, Onecall has an impeccible reputation.

My family and I have bought numerous hk remans on ebay. Have one failure to date which is the cooling fan on an avr7550, but still under warrantee. hk honors warrantees only by authorized dealers so you have to be careful. hk has a list of authorized dealers on their website, and if the seller is not listed with them, I would check with hk before buying.

Glassaudio1, I am not intuitive with these modern machines either. Maybe that's why the hk990 and I get along. You have to push "enter" a lot. Does that help?

In regard to the companion cdp HD990, if you haven't bought it, I probably would not. I'm sure the electronics are high quality; the problem is that the machine is so light and that includes the transport. I'm using an old hk cdp that was made between 1988-92 as a transport. The HD7600 and mk11 are 20 pounders with solid transports, and I use the hk990's onboard DA converter which is high quality. Switching out the hd990 for the hd7600 and using the hk990's DA converter was a significant upgrade.

You need a heavy solid transport the variable being the quality of the circuitry which transmits the digital signal.
I purchased an HK 990 about two weeks ago. It has definitely changed the sonic signature of my system for the better. Previously I was driving a pair of Usher Dancer Mini loudspeakers with a Cambridge Audio Azur 840A v2 amp. I received an HSU ULS-15 subwoofer for Christmas, but was never able to integrate it into my system to my satisfaction, as my crossover options were limited to running the Ushers full range and attempting to fill in the frequencies below that with the sub. It went low, but not clean enough. It became obvious to me that I needed some type of bass management system, but I cringed at the idea of replacing my amp with an AVR. Then I stumbled upon the HK 990. Dual mono configuration producing 150W per channel (seems like more). Best of all it had what no other stereo amp that I was aware of had......bass management. I bought one.
First of all let me say that lifting a dead donkey would be easier that picking up this amp! The damn thing is heavy! I wrestled it into my rack and replaced my DacMagic with a toslink cable going straight from my music server to one of the optical inputs on the HK 990. I then set the HK 990 to crossover my speakers at 80HZ. The change was immediately noticeable. The bass was cleaner and actually seemed to go lower than before. But, what I didn't bargain for was the improvement in the upper registers as well. With the DacMagic/CA 840A combination, the focus seemed to be on the treble. With the HK 990 the mid-range became slightly more prominent. I guess the term audiophiles like to use is "sweet". Listening to Beethoven piano sonatas, I noticed a realistic percussive property to the leading edge of each note that I have never noticed before. I've only had this amp in my system for a little over a week, but I already love it. With four digital inputs, lots of analog inputs, bass management and oh correction software, all packed into a box that produced over 150 watts of super clean power. What's not to love?
Cool! I've got my crossover set at 40hz especially because I made a bad decision and am now stuck with a pair of Paradigm PDR10's. They are so pathetic that they wheazed once and I'm afraid I will destroy them. The power light dims also when they get a heavy drum. But the current set up is working quite well.

How do you like your sub? I need to sell mine and replace at some point.
The HK 990 is now discontinued. I wonder if there's a replacement in the works.
Crutchfield web site. Could be just that they are discontinuing carrying it.
The HK990 is not discontinued. It's just that now it looks like its availability is pretty much limited to just buying direct from Harman Kardon. In the past it was sold through other outlets such as Crutchfield, but for whatever reason, it seems that HK stopped such distribution in favor of selling direct.

PS. Other than the HK website store, there is one other place I know of where new HK990s are still being sold, which is through the Citi Easy Deals website for anyone with a Citibank credit card that offers reward points that are tied to Citi Easy Deals.
It is still available at and a seller on amazon that I don't know.
Sorry for posting bad information.
I bought mine directly from Harman.
@ Arnettpartners

I like the sub, but I wasn't so sure until I put the HK 990 into the system. Raising the crossover point from 45 to 80hz and removing all the frequencies below 80 from my Ushers cleaned the bass up significantly. I couldn't do that with my CA 840A. A couple of professional reviewers are claiming this amp produces close to 200 watts per channel (HK claims 150). But, it isn't just a brute. It's a brute with lots of finesse.
We all screw up like that. Not an issue.

thanks. Yes, I've heard it said that subs are not very successful without bass management.

I agree on the hk990. My info is that hk has essentially not changed its amplifier design since Dr. Matti Otala designed the mythical Citation XX the commercial version of which were the hk775 mono amps. And I do think hk has a signature sound. Yes, I agree. It's exciting, warm and detailed. Hard to beat.
I'm Thinking about picking on of these up. However, I also am intrigued by the Marantz PM 15S2. Does anyone have any info about comparing the two of them. I am leaning towards the HK990. But I've heard a lot of good things about the Marantz.
I haven't heard the Marantz PM 15S2. I like Marantz generally. What bothers me is that Stereophile states the S/N line level of the Limited Edition as -89db which seems like a dark ages spec to me. Stereophile states the hk990 line level as -109db. I think hk calls it -100db. I think the last time I had a piece under -100db was an Acurus pre from the early 90's but I don't think S/N was that low. I think I owned an hk amp that had S/N line level at -110 many years ago. This is off the cuff so I stand to be corrected.

It doesn't bother me that the Marantz does not double down on power like the hk does. Most amps don't. But 150w/80hms has become pretty much standard for me. I realize some run lower powered amps successfully. My speakers are not efficient, and I'm greedy for power.

The proof is in the listening, and maybe others have auditioned the Marantz and can offer better opinions.

These are just my initial thoughts which are no substitute for an audition.
you can order from harman kardon as refurbs for $999 with free shipping. I ordered one today.
Cnguyen, be careful. HK is typically out of stock on refurbished stock.
Forster, after a failed attempt at ordering a refurbished HK990, (First they told me it was available only to find out through an email days later that they could not fulfill my order because it was out of stock), I asked them if they would allow me to prepay for one and they could send it when it became available. They said that would be fine so I went that way. I received it in about a week and a half. So my advice to anyone looking for one through Harman's refurbished products website is to call and ask directly don't rely on the website to tell you when one becomes available. They go too fast.
A very strange thing happened with my unit this past weekend. I have all my sources routed through my HK990. I was watching a golf tournament and after it's conclusion I shut the system down as usual. First I turn the volume on the amp all the way down, then turn off the TV and cable box. But, on this occasion the volume coming from the loudspeakers did not change. The display indicated the volume was being lowered, but the actual sound remained at a constant volume. I then attempted to turn the volume up, but again it remained constant. Only after I turned the power off and back on did the HK990 resume normal operation. A couple of people on a European forum said that their HK990 had suddenly gone to full volume without provocation. I wonder if there is a relationship between their issue and what I experienced last weekend. This amp sounds great and has worked flawlessly save for this one hiccup. Has any other owner experienced anything similar?
I'm just responding because no one else has. This anomaly hasn't happened with my system. And I'm techno challenged.
The "full volume" experience sounds scarey in terms of the damage it could cause.

I don't know if I mentioned here that the LED's in the middle of the read out would go out when I switched functions. When I powered off and on again, the lights were restored. HK had not heard of it and even sent me a new amp which behaved the same way. Then I moved the system to the basement, and the issue was resolved.

Steve at Empirical Audio told me that ground loops had caused the anomaly. Gound loops are reduced when the entire system is on one circuit which it was in the basement and which it was not previous.

I get the impression that ground loops are inevitable when several devices are connected in one system, and the goal is to reduce them as much as possible. And now I wonder what other mysterious and unexplainable phenomena ground loops can cause.
The letter-on-and-off thing in the dot matrix display happened to me sporadically too as it did with Arnettpartners.
To Danoroo (and ArnettPartners): I have been a longtime lurker on these forums and never posted until now. I thought I was going to be the only one who had ever had this anomaly (since the HK 990 seems to be somewhat rare). You're two posts confirm my suspicion on what was causing this scary phenomena.

I had the error with the volume happen 3 times, and I finally narrowed it down and can probably reproduce it (not that I would want to). I guess since it is a real issue I will call it the HK 990 runaway volume issue. If you can point me to the european forum that describes this, please do as I have not ever seen this pop up before publicly.

Let me explain how this happened to me:
In my normal listening setup, I primarily listen to a Dual 721 TT connected to the HK 990 via the MM inputs and ground wire connected there too. I also have a media comp. connected via toslink-1 and cable box connected via toslink-2. I have used the amp with no issues, only immense satisfaction at how awesome it sounds connected to these devices and outputting to KEF LS50 speakers and Klipsch 12 sub. Amazing sound. Maybe more on that later.

However, I have several other TT's that I like to rotate in to my living room from time to time. To keep from having to disconnect the main Dual, I purchased an Emotiva XPS-1 phono preamp and would connect that device to one of the other HK 990 RCA inputs (such as CD or tuner). I then connect whatever TT I desire to the Emotiva (along with ground wire to Emotiva). Note that the separate phono pre has a power supply connected to same wall outlet.

One afternoon I decided to connect a Sony TT to the XPS-1 and do some listening (I had a new stylus I wanted to hear). After listening a bit I was changing volume with the remote and all of the sudden the volume rapidly started getting louder and louder (the number in display was not changing). It quickly rose to deafening sound and I rushed across the room to turn it down as the remote was not helping. I visible was horrified at the head-busting distorted sound and the noticed the drivers on my KEF's were going to maximum displacement.I hit the power button and started to cringe as I thought the worst had happened to my system and fairly newly purchase KEFs.

I monitored things closely as I powered it back on and tried to listen to the Sony TT again. After a few minutes the volume started to runaway again but I shut it down before it got out of hand.

I disconnected the Emotiva amp (thus the Sony TT too). I was able to safely listen to the other inputs (inlcuding Dual TT) just fine from then on. Luckily my system was unharmed and the KEFs are fine :).

After a few days I decided to troubleshoot this and I removed the Dual from the system. I then connected the Sony T to the primary MM inputs on the HK 990. No problem, I never had the runaway volume issue. Weeks went by and I wanted to try the 2 turntable setup again and I redid the same configuration as before (Dual on primary inputs, Sony on Emotiva). The volume got wacky once again after some time and I decided I simply cannot have the Emotiva plugged into the other inputs, there is something electrical that is causing the HK 990's computer or outputs to go nuts.

After seeing your comments. It does seem possbly related to the ground loop. Let me know the european forum link... I would like to compare notes.

I don't want to change to a different amp as it does everything I need (I just have to be careful with the 2 tt setup) and I love the sound too much. It is an incredible combination with the KEF's which ar3 4-6 ohm speakers and the HK is perfect for them as it can push 300 watts to 4 ohms!

However, I am going to audition a Schiit Uber DAC this weekend with the HK 990 to see how external DAC compares with the included one.
Very informative. Thanks. I think lurking is good. I should have done more of that.

FWIW, it seems to me no doubt that your experience supports the ground loop theory. I'm sure Steve Nugent from Empirical Audio would have a comment. He probably doesn't read this particular forum. But it wouldn't hurt to ask.

When I was a newbie years ago and there was no internet for support, I drove a rod into the ground outside my window and grounded my system to it. I thought the sound was improved. I asked my dealer about it, and he gave me that "you're really going off the edge" look. So I thought I must have had a good imagination in the same way that placebos work well sometimes. Now I think I should try again. Connecting a ground to plumbing might work too.

I can't give you info on the European forum. I've had emails from Europeans, and sounds like the hk990 is popular there. Someone else here probably can.

I wouldn't be so sure that the hk990 is rare. HK isn't popular on audiogon, but I suspect sales are good or it would have been discontinued. The absence of hdmi in the hk990 ( I think it came out in Europe in '09) outdates it and should make it unattractive to consumers. But I think that the SQ combined with advantages it has over separates has earned it a market share. I think hk stock doubled last year on NYSE.
Here is the URL to the Euro thread I mentioned. You will need to have your browser translate as it is primarily in French. Also note the length of this thread. It has been several months since I read this thread, so I can't say specifically where the "runaway volume" issue was first mentioned (it seems like it was in the first 100 pages or so). I have not had a repeat occurrence of the incident I described, but it sounds like you are on to something with your assessment. Thanks for your input and here is the link to the thread:
I have a faulty HK990. When I connect an optical input and switch on the amp, it throws an error 005 followed by a message DSP firmware corrupt, reload DSP firmware. I have tried the firmware reset procedure of using Speaker1 and Level button, but the error still shows up.

Now, if I don't connect an optical input, there is no error, but there is no sound even in direct path setting.

Googling gave some pointers to a faulty SRC 4392 chip. If that is indeed the case, is it just about replacing that chip or this is something only Harman Kardon can do because SRC 4392 has some HK firmware?

I have approached Harman Kardon in India and they have been very reluctant to help.

Any help will be really helpful. What are my options without having to go through HK?
I have a faulty HK990. When I connect an optical input and switch on the amp, it throws an error 005 followed by a message DSP firmware corrupt, reload DSP firmware. I have tried the firmware reset procedure of using Speaker1 and Level button, but the error still shows up.

Now, if I don't connect an optical input, there is no error, but there is no sound even in direct path setting.

Googling gave some pointers to a faulty SRC 4392 chip. If that is indeed the case, is it just about replacing that chip or this is something only Harman Kardon can do because SRC 4392 has some HK firmware?

I have approached Harman Kardon in India and they have been very reluctant to help.

Any help will be really helpful. What are my options without having to go through HK?
I haven't checked this post for a long time, not that I can be helpful at all. Is there an authorized hk service center in India? An hk service center would be the key, I think. Good luck.
Hi all, wondering if there are any updates to your experiences with the HK990? I took the plunge and bought one that I knew would have issues. My issue is a hum/whistle/distortion across all sources and modes, does not go away not matter what. It is a constant level, so if you really turn it up, past casual listening levels it goes away. I suspect a vented cap, very visible and right on the preamp board where the power comes in form the transformer(smaller 3rd transformer). Likely going to get it fixed.

Comment on the ground loop issue. This unit is not grounded, would grounding it help?