Harman Kardon HK 990 integrated amplifier
The very first amplifier I bought was a Harman Kardon PC-200, aka The Prelude. It was a 10Wpc integrated, but I chose it over the competition for some of the same reasons that the HK 990 has appealed to me. Almost all amps back in the1960s had a plain cake-pan chassis with tubes, capacitors, and transformers studding the top. Integrated amps had the standard four knobs on the front for input selection, volume, bass, and treble. The HK PC-200 had an enclosed black chassis cage that formed a graceful cowl over the brushed-copper front panel and the six matte-black knobs: for Input selection (with three phono turnover settings), Volume, Bass, Treble, Loudness contour, and Treble rolloff. In addition, it had a Rumble Filter switch. The PC-200 was not only more beautiful than the rest of the push-pull competition powered by EL84 tubes, it also had more useful features. (Take that, you fans of the Grommes Little Jewel!). Over the decades, H/K products have always been stylish and innovative, but in today's fractured marketing world, most such creative energies are applied to audio/video receivers and lifestyle products.
The HK 990 is a product for the serious audiophile: a full-fledged, analog, two-channel integrated amplifier with serious output clout (claimed instantaneous output current of ±200 amps). It also has digital inputs to handle modern source components, and offers bass management as well as home-theater bypass for the left, right, and up to two low-frequency effects (LFE) channels. Some other integrated amps have some of these features, but the HK 990 is, as far as I know, unique in being a two-channel product that includes measurement-based room equalization. And it's gorgeous.
Out of the box
Having seen the glossy catalog sheets, I was unprepared for the HK 990's weight and solidity. My sample had been handled by other reviewers, and its volume knob had come off in the carton. But after I'd maneuvered this 43-lb baby out of its swaddling, I popped the knob back on, settled the amp in place on its four damping pods, and plugged it into the AC line.
A thin black line divides the HK 990's front panel into upper and lower halves. On the upper half are the large alphanumeric display and illuminated volume knob, while in the lower half are only the Harman Kardon logo and a headphone/microphone jack. Close examination reveals that much of the thin black line comprises eight thin pushbars whose labels are dim and small. The reticence of this concession of convenience to design leaves the front panel looking cool and clean, and anyway, the most common controls also appear on the multifunction remote control, where they're more handy, and more easily differentiated by shape and position.
The rear panel's many connectors are grouped into analog inputs (including XLR, moving-magnet, and moving-coil), digital inputs, and HT processor bypass inputs, to be directly connected to the HK 990's power amp stage. A look inside the HK 990 revealed that these groups reflect the array of specialized circuit cards on the main chassis. One input, looking curiously like an RJ-45 Ethernet jack, is labeled HRS, for High Resolution Synchronization, a proprietary H/K connection with which the HK 990 can be linked with the digital outputs of H/K CD players, such as the matching HD 990. The HRS link carries both the system and data clocks of the amplifier and the datastream from the CD player, which locks itself to the amplifier's clock to ensure a jitter-free connection. (I am not a fan of proprietary interfaces.)
The only modern input sources the HK 990 seems to lack are Ethernet and USB. While I would certainly welcome their inclusion, I sidestepped the omission by plugging a Logitech Squeezebox Touch music server into one of the H/K's digital coax jacks. The HK 990 also offers L/R analog and dual subwoofer RCA outputs, and a digital output jack for recording. In addition to power, RS-232, and trigger and IR ins/outs, there are two sets of multiway speaker binding posts for each channel's output, these selectable via front-panel switches.
Setup for the new millennium
I hooked up the HK 990 to my Sony XA-5400ES SACD/CD player, Oppo BDP-95 universal Blu-ray player, and Squeezebox Touch, and to a pair of Aerial Model 7T speakers and my trusty JL Audio Fathom f113 subwoofer. When I touched the On/Off bar in the left corner of the HK 990's front panel, next to the amber standby indicator, both that indicator and the rim of the volume knob glowed a soft blue. Gracious in demeanor as well as appearance, the large blue display said, "Setting up, please wait," and in a few seconds the HK 990 was ready to go.
That's the simplest way to get the HK 990 up and running, but it bypasses what makes this product special. Its proper setup is a procedure akin to setting up an AVR. First, you choose which input jacks to associate with which input selection name; eg, balanced analog, unbalanced analog, optical or coaxial digital. For the phono selection, it's MM or MC (footnote 1). Next, you need to choose between Manual or Automatic setup of bass management. This is easy. With Manual, you inform the HK 990 whether you're using one or two subwoofers, then pick a single crossover frequency from 20 to 200Hz, in increments of 10Hz.
More wisely choose Automatic and you enter H/K's EzSet/EQ mode. This begins with the same enumeration of subs, and you can specify a crossover frequency or let EzSetEQ do it. From there, the Automatic route opens up a series of measurements and calculations that result in the system being equalized in three bands. Plug the calibration microphone (provided) into the mike/headphone jack on the front panel and follow the prompts on the HK 990's display (or in the owner's manual):
1) With the mike at the primary listening position, the HK 990 sends a sweep tone to each speaker, and uses the information it collects to apply a Far Field mid-frequency (20Hz1kHz) correction to the main speakers.
2) Place the mike 60cm in front of each main speaker, and the HK 990 emits a sweep tone that it uses to apply a Near Field, high-frequency (>1kHz) correction to the main speakers.
3) Place the mike back at the primary listening position. The HK 990 sends a low-frequency sweep of considerable power through each subwoofer, then applies a BassQ correction to the subs.
EzSet/EQ also sets channel levels and crossover frequency, but these can be easily tweaked afterward. H/K also gives the user considerable freedom in applying the EQ. You can switch, on the fly, with the remote control among DSP (no EQ), EQ1 (BassQ only), EQ2 (BassQ and Far Field), and EQ3 (BassQ, Far Field, and Near Field). In fact, since the HK 990 can digitize analog inputs, the list of options is longer and runs from Direct Path, DSP Path, EQ1, and EQ2 to EQ3.
Footnote 1: I didn't really test the HK 990's phono inputs, but I did dust off and hook up my Heybrook turntable to determine that they at least worked. For what it's worth, they sounded better than my Audiolab 8000PPA phono preamp.