Integrated Amplifiers

Harman Kardon HK 990 Integrated Amplifier and HD 990 CD Player

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HK 990 Integrated Amplifier

My first listening experience with the HK 990/HD 990 duo was a bit of a revelation for me. Typically, an old Denon 3802 A/V receiver powers the Paradigm Reference Studio 20s that sit in my den listening room. While I've heard enough high-quality gear to realize my Denon is by no means state-of-the-art, I was completely unprepared for how much better the HK 990 made things sound. I typically run through a set of demo tracks when I first fire up a component to get an overall feel for how a new piece of gear sounds and to get a "pre-break-in" benchmark. As soon as I started playing my first track my wife came downstairs, walked into the den and said, "Wow, it sounds so much clearer." She stood and listened for about a minute, saw the evil glint in my eye and then asked, "What are these going to cost me?" She knows me far too well. What really shocked me was that I had just fired the HK 990 up, so there had been absolutely no warm up or break-in time yet. Things could only get better from here and I rubbed my little paws together with glee.

Harman Kardon 990 Integrated Amplifier and HD 990 CD player for the Audiophile

I used the HK 990/HD 990 for about four weeks (about 100 hours) of casual music listening before settling down for any critical sessions. To be honest, I did not notice any appreciable difference in sound quality versus the out-of-the-box state, so break-in is probably not necessary with the HK 990. I did feel that the amp needed about 15-20 minutes of playback before sounding its best though, so keep that in mind when you demo the product. I did my first listening session with my Yamaha changer as the source, so I could get a feel for the sound of just the HK 990. I kept all DSP/EQ modes off, keeping things in the most pure "Direct" mode. I started with my long-running favorite demo, Reference Recording's "Symphonic Dances" by Rachmaninoff (RR-96CD). In a word, the sound was stunning.

The first thing I noticed was the absolute clarity of the signal. The noise floor was so much lower than I was used to. There was no hash or grain to the sound, which just made musical details stand from the background. This led to a vast improvement in apparent detail, without any extra brightness or glare. Even detail in the bass was improved, making things like tympani hits easier to distinguish from one another. Treble detail also improved remarkably, without any extra bite or brittleness to the sound. Mid-range tones were clear and beautiful. I also found that the soundstage width and depth had increased noticeably. Imaging was improved as well; it was now easier than ever to pick out where certain instruments were arranged in the mix. The most noticeable improvement had to be in the bass though. The HK 990 took firm control over the 7" midrange/woofer in my Studio 20s, resulting in much tighter, punchier bass attack. Bass definition, pitch, and rhythm were also noticeably improved. Even more surprising to me was that it sounded like I was getting slightly deeper bass as well. Perhaps it was the increased power of the HK 990, but all of these attributes helped give the music a large increase in dynamic punch, which suited this type of large scale symphonic track very well.

Harman Kardon 990 Integrated Amplifier and HD 990 CD player for the Audiophile

Next I queued up "Mediterranean Nights" (Avalon B0001LJCZW) and put on track 13, "Hasta Pronto." This track has a quick moving natural bass line that can get a bit muddy on a less revealing system. It was remarkably clear and easy to follow with HK 990 in my system and also seemed to reach a bit deeper as well. Besides the bass, the Spanish guitar sounded just right and the hand claps that run throughout the song were completely natural sounding. I also played track 9 from this disc, "Con Ternura," as it is one of the most beautiful, yet haunting guitar melodies I've ever heard. The tone was perfect, with natural decay to the individual notes and a great sense of reverberation (probably studio enhanced just a bit) from the body of the guitar.

Harman Kardon 990 Integrated Amplifier and HD 990 CD player for the Audiophile

Harman Kardon 990 Integrated Amplifier and HD 990 CD player for the Audiophile

Vocals tracks shined just as much as instrumentals through the HK990. I put on the 2-channel SACD track from Diana Krall's "Love Scenes"(Verve B0002DSUEI) and skipped right to track 11, "My Love Is." While this disc sounds great on just about any system, I was particularly impressed with it through the HK 990. The natural bass intro was awesome, and Krall's voice sounded even smoother and sultrier (is that even possible?). After listening to a few other tracks off the disc, I moved over to Melody Jardot's "My One and Only Thrill" (Verve B002RD4UZ4). "Who Will Comfort Me" and "Your Heart Is As Black As Ice" both sounded wonderful, with Ms. Jardot's beautiful tone ringing through clearly. This CD is not as slickly produced as the Diana Krall SACDs, but it still sounded great.

After playing some additional rock and electronic tracks, I realized that I had never heard my Paradigm speakers sound so good. Maybe it was just equipment synergy, but the HK 990 and Studio 20 V3s made for a marvelous pairing. The HK 990 made my Paradigm's sound like a far better speaker, and they aren't too shabby to begin with. Even so, I found myself wishing that I still had the excellent Dynaudio X16s (see my review here) around. The tonal qualities and increased resolution of the Dynaudios plus the beautiful tone, clarity, and punch of the HK 990 would most likely be a match made in heaven. Bottom-line, the HK 990 is certainly up to the task of driving any high quality "audiophile" speaker.

HD 990 CD Player

As it was obvious that the HK 990 had some incredible sonic chops, I now focused my attention on the HD 990 CD player. The first thing I did was compare the different outputs of the HD 990 using the same demo tracks I played on my Yamaha changer. The analog outputs were smooth and refined, and presented a bit more musical detail than my less expensive Yamaha changer. Given that the HD 990 uses a single Analog Devices AD1955 DAC per channel combined with a 24-bit/384kHz asynchronous sample rate converter, I was not too surprised at the quality of the output. Due to the lack of any extra balanced XLR cables I was unable to test out the true balanced outputs of the HD 990, but if I were going to run analog I'd definitely use the balanced connection. From my experience a true balanced connection sounds a bit better, plus it outputs a higher level signal.

Harman Kardon 990 Integrated Amplifier and HD 990 CD player for the Audiophile

Next, I tried the digital outputs. The coaxial digital output sounded slightly less rich than the analog outputs and seemed to have a slight edge to it as digital often does. I reconfigured the CD input on the HK 990 to accept a digital signal via HRS-Link and ran through my test tracks again. It took me about 30 seconds of "Mediterranean Nights" to realize just how much better digital sources sound when you can remove most of the jitter from the signal. The sound was more smooth and natural, without that slightly harsh glare inherent to most digital music. Things simply sounded more "analog" to me. While these differences are subtle, the longer you listen the more you can spot them. While listening to Charles Brown's "Alone at the Piano" (Savoy Jazz B00015HVHO), I started to notice how individual piano notes seemed to ring truer. Each note would decay more slowly into the background. As I grew up in house with two piano players, this increased sustain stuck me as completely natural and much more correct than the clipped notes I typically associate with digitally-reproduced piano. Switching back to "Mediterranean Nights" I noticed a similar effect on guitar notes. Individual notes just seemed to hang in space a bit longer, which gave the music an increased sense of body and impact. The music just seemed closer to what you hear during a live performance. As much as I enjoyed the HD 990 via its analog outputs, I used the HRS-Link connection for the rest of the review period. Via HRS-Link, the HD 990 produced the best Redbook digital sound I have ever heard in either of my systems.

Since I was so impressed with the sound of the HK 990/HD 990 pairing, I asked Harman Kardon to explain exactly how HRS-Link worked. Per Harman Kardon's engineering department "In order to avoid too much A/D and D/A conversion along the signal chain, it is preferable to keep the signal in the digital domain from the source to the processing point. While using a CD player, you can use the SPDIF connection thus you keep the signal in the digital domain. But in doing so, you rely on the SPDIF receiver PLL to extract the clock signal, so quality may vary a lot depending on the signal integrity. In order to avoid the possible increase of jitter related to this stream reconstruction inside the receiver we include the Ultra-Low Jitter Digital Connection (HRS-Link) between the source unit (HD 990) and the HK 990. The HRS-Link uses a RJ45 connector and some LVDS drivers/receivers (Low Voltage Differential Signaling) working at high frequency and carrying the following signals:

  • System and data clocks of the amplifier
  • Data stream from the CD player

When the HRS-link is established the CD player doesn't use its internal clocks but locks itself to the external clocks delivered by the amplifier. The data extracted from the disc is then stored into buffers asynchronously and formatted synchronously to the amplifier clocks into 24 bits and up sampled to a 96 kHz stream. The result is a jitter free connection between two units, similar to having the CD player inside the amplifier. Jitter is less than 1ps RMS." While I lack the test gear to verify the amount of jitter, my ears tell me this spec is spot on.

I also spent some time feeding MP3s (128kbps - 320kbps) through the HD 990 and was impressed by how the up-sampling of the HD 990 managed to remove some of the brittleness and lack of musical body that I often attribute to highly compressed sources. While I could still tell how inferior MP3 is to even CD, the tracks were at least listenable now.

With the HD 990 feeding Redbook CD to the HK 990, it was time to see how effective the EZSet/EQ was at correcting a digital signal. With the dedicated button on the HK 990's remote it was incredibly easy to cycle through EQ settings rapidly. EQ1 only engages room correction for the frequencies covered by your subwoofer(s), but as I didn't have any connected there was no real change to the sound. EQ2 adds midrange correction to the signal and did appear to smooth out the frequencies up to 1KHz. While the midrange did sound a bit smoother overall, the lack of correction in the treble now made the sound a bit unbalanced, as the treble now sounded a bit over-emphasized. Hitting the EQ remote button once more moved the HK 990 into EQ3, which applies full-spectrum room correction. The extra treble emphasis was now gone and the sound at my listening position was very nicely balanced. However, as I typically find with room correction systems the EQ seemed to take a bit of the life away from the music. There was a subtle loss of dynamics and clarity, though it was less through the Harman Kardon pair than through other correction systems I've heard. To my ears (and in my room), the EZSet/EQ system works best in an "all or none" mode. Hitting the EQ button again brings you back to an uncorrected state and lets you hear the difference for yourself. If I had a room with larger peaks and suck-outs I would probably leave EQ3 on all of the time, but as my room is pretty well balanced I spent the remainder of my time with the EQ off.