Integrated Amp Reviews

It's only an amplifier
For all its bells and whistles, the HK 990 is a stereo amplifier and must be judged as such. With either the Sony XA-5400ES or Oppo BDP-95 connected to its balanced XLR analog input and the input mode set to Direct Path, the sound coming out of the Aerials was uncompromised. The bass in Pipes Rhode Island (CD, Riago 101), a compilation of pipe-organ recordings engineered by our own John Marks, was clean and taut and loaded the room well. Inner voices were exquisitely delineated. With the divine Lorraine Hunt Lieberson singing Neruda Songs, composed for her by her husband, Peter Lieberson (CD, Nonesuch 79954-2), there was an eerie sense of a lively, balanced presence to her voice and a good presentation of the Boston Symphony (led by James Levine) in their home venue, Boston's Symphony Hall. The power—for example, with Messiaen's brilliant and massive Turangalîla-Symphonie, in the recording by Hans Vonk and the St. Louis Symphony (SACD/CD, Arch Media Archives/Pentatone PTC 5186 320)—was almost staggering. The same was true with Dead Can Dance's Into the Labyrinth (CD, 4AD 45384-2): the HK 990's impressive bass imposed no limitations, either on more delicate instrumentals or on Lisa Gerrard's soaring melisma. The sound from the same source components via the H/K's unbalanced analog RCA inputs was marginally less secure but not disappointing. I listened to a wide range of other recordings, and the HK 990 offered eminently satisfying performance through the Aerial and the B&W speakers. If I could settle for listening to music in only two channels, I could live happily with the HK 990.

Now it gets messy. To enjoy the HK 990's bass-management and EQ capabilities, you must choose a digital source or—horrors—redigitize an analog source. I figured the best way to decide how to proceed would be to compare the above sources Direct Path vs "DSP Path," and then each against the HK 990's coax S/PDIF feed, which accepts signals up to 24-bit/192kHz. I was told by H/K that the 990's D/A "bit depth is 24-bit . . . up to 96kHz without truncation." Even with instantaneous switching, I found it all but impossible to distinguish between Direct Path and S/PDIF; each mode was transparent to the particular player's sonic personality. That attests to the quality of the HK 990's D/A conversion, which is based on a pair of AD1955 chips, a two-channel DAC capable of 24/192 operation; and while H/K provides only sketchy technical data, I was assured that the bandwidth of the HK 990's analog outputs extends cleanly to 45kHz.

What about redigitizing the source? Here my H/K sources told me only that redigitization is 24-bit, and offered no information about the sample rate. Audibly distinguishing between Direct Path and S/PDIF via the DSP Path route was hard to do. I could just barely distinguish the "DSP" mode for the analog inputs from the other options, and even then, only when I forced myself to attend to such niggling details as the decay of cymbals or, indeed, Hunt Lieberson's voice. It required an almost surgical vivisection of the music. I restricted my listening to DSP Path mode for a week and heard nothing lacking, though a return to the A/B/C comparison had the same outcome as before. No biggie!

But it's more than an amplifier
The above observations are preamble to saying that a digital source component should be used as such with the HK 990, but that analog sources won't suffer if you redigitize them. Either option opens the door to the blandishments of bass management and/or room EQ. Switching an analog source (albeit from a digital player) between Direct Path (without bass management or EQ) and DSP Path (with bass management but no EQ) was another subtly strenuous task. That there was no apparent change in balance or voicing validated the success of the HK 990's Automatic setup routine: The chosen crossover was at 40Hz and the Fathom f113 sub's output was set to +3dB relative to the Aerials'. On the other hand, the Aerials seemed to gain nearly an octave of low-end extension. I say that because the sub was completely unlocatable by ear. I kept going over to touch the Fathom f113's cone to confirm that it, and not the Aerials, was producing those deep shuddering sounds.

I then tried the EQ results from EzSet/EQ. I did some quick measurements using Dayton Audio's OmniMic (see "Music in the Round" in the November issue) and found that the equalization did not change the overall nature of the in-room frequency response, which, measured at the listening position, gently trended down 6–7dB from 50Hz to 18kHz. Looking at the effects of each variant of EzSet/EQ, it was apparent that BassQ (EQ1) made for a smoother transition from sub to main speaker in the 50–100Hz range. Adding the Far Field EQ (EQ2) reduced the variability below 500Hz, and Near Field EQ did something similar for the range above 1kHz. The audible effects were quite subtle. The tonal characteristics of the Aerials and the room were unchanged, but BassQ (subwoofer) and Far Field (below 1kHz) enhanced overall clarity and expanded the soundstage, particularly in width. The effects of adding Near Field (above 1kHz) correction (EQ3) were elusive; I tended to stick to EQ2. I got similarly satisfying results when I swapped, the B&W 800 Diamonds for the Aerials. It was not so much an "Ah-ha" experience as "Ah, that's really better."

Overall, I was able to accomplish with the single-box HK 990 almost everything that I could with the combination of Meridian Reference 861, Parasound Halo JC 2 BP, and McIntosh Labs MC303. Was the H/K less potent than the Mac? Yes, but I had to force myself to listen at volume levels high enough that I could hear a difference—much higher than I would ever actually listen to music for pleasure. Was it less transparent than the Halo JC 2? Yes, but my ability to hear that difference depended on the recording. Was it less capable than the Meridian? Yes, the Meridian provides more channels and more processing options. Still, I could go from one setup to the other and not feel that the HK 990 was any less satisfying . . . with two-channel music.

Conclusions
I found that Harman Kardon's HK 990 delivered on all its promises. Its power amp is very strong and agile. Its purely analog performance, from input to speaker, is worthy of the highest-quality sources and signals. Digital sources are handled cleanly and at high (24-bit/96kHz) resolution. But most important, the HK 990 brings modern audio features to a two-channel system by providing useful bass management and effective room/system equalization. I've always believed that, given adequacy in all components, speakers and room acoustics will be the biggest determinants of a system's overall sound. The Harman Kardon HK 990 integrated amplifier not so much refutes as confirms that belief. Unlike purely analog amplifiers, it can actually improve the sound of your speakers in your room. At less than $2599, the HK 990 should be on every audiophile's shopping list.