Krell KRC-HR preamplifier & Audio Standard power amplifier
By Wes Phillips   •   October, 1996 About a decade ago, I read in Stereophile about the SRC, an add-on remote-control unit manufactured by Acoustic Research. I bought one the next day ('swhat happens when you work across the street from a hi-fi shop). Suddenly I was able to make incremental changes in volume and balance from my listening position—and let me tell you that that's the way to do it. What a phenomenal difference in realistic dynamics and soundstaging.

But there was a fly in the ointment. My system wasn't state-of-the-art by any stretch, but it was reasonably transparent. With the AR remote in the circuit, it was noticeably less so. As much as I hated to see it go, go it had to—and did. (I must also confess to having had a strong strain of Audio Calvinism at the time—deep down, it didn't feel right to have convenience in a high-end system.)

But it did make me wonder: Since remote control offered such obvious benefits, why didn't the real high-end manufacturers explore ways to accomplish it without sonic tradeoffs? Why couldn't we have it all?

What a difference a decade makes. Today you'd be hard pressed to find a major high-end manufacturer who doesn't offer a full-function remote-controlled preamp. But let me tell you, it still comes as a shock when it's done as well as the Krell KRC-HR.

You can tell it's a Krell
'cause it's swell
Did I say full-function? The Krell is first—and foremost—an extremely sophisticated preamplifier. Its signal stages run in high-bias class-A and it features digital switching as much as possible divorced from the signal path. Volume control is achieved through an electronic, two-channel gain network that features over 300 discrete attenuation steps. No capacitors are used in the audio circuit paths, and the circuits themselves are laid out on high-quality four-layer glass/epoxy boards which, Krell claims, offer superior grounding as well as increased power stability.

The preamp has two balanced inputs (pin 2 hot, non-inverting), which utilize complementary circuits for increased linearity, as well as four single-ended inputs. One of these, S1, can accommodate Krell's Standard or Reference Phono Modules (which also mate with the KSL and KSL-2 line stages), while S4 can be switched for unity gain throughput. Single-ended and balanced outputs are provided; both are active at all times, meaning the KRC-HR can be used to control power amplifiers in two separate systems—assuming equivalent gain is desired in both at all times.

The preamp's heavy-duty power supply has its own chassis, whose umbilical is secured by nine-pin computer-cable-style connectors at both ends. Krell cautions strongly that the power supply be connected solidly to the preamp before being plugged in—always a good precaution when using an external PS.

The front panel is a tribute to uncluttered functionality. Its single knob—the gain control at the far right—even has an LED indicator set into it, allowing you to judge the level setting from across the room. All other switching is accomplished through oval-shaped soft-touch activators, each accompanied by a status-indicating LED. On the far left, above the mute switch, the six input selectors are arrayed in two rows in a pattern resembling an I Ching hexagram. Slightly to the right of these, in a vertical line, are the tape switch, the gain selector (6 and 12dB settings), and the polarity-inversion switch. In the middle of the front panel is a heavy band of black-anodized metal—matching the preamp's endcaps—which contains a wide I/R receptor window set above the trademark six-screw Krell nameplate. To the right of this is a twin row of five balance switches (incrementally indicating 1dB of adjustment for each channel) and the level-adjustment knob. All controls are replicated on the remote.

The fit'n'finish on the KRC-HR is first-rate. All metalwork, including XLR and RCA connectors, is superb. The unit is solid, built like a tank. Open it up and gaze at the circuit boards: they are gorgeous, but—even more to the point—they're jammed full of the highest-quality parts imaginable and affixed with remarkable precision. Krells don't come cheap, but you'll never wonder where the money went.

Leaving Krell enough alone
A lot of what I like about the KRC-HR is what it doesn't do. It doesn't hum, add noises, or call attention to itself in any way at all. Like most inhabitants of our modern age, I've become inured to the low levels of obtrusive noise that pervade our environment: fans, motors, transformers, fluorescent lighting ballasts—heck, even buzzing light-bulb filaments. Let's face it, we live in a miasma of unwanted sounds. But the Krell doesn't contribute to it at all; not only is it—and its power supply—dead quiet in operation, but its addition to the signal is virtually nil—far below my ability to perceive it.

This lack of noise makes its resolution about the highest I've ever experienced. I've heard stuff in favorite recordings that I've never heard in 20 years of listening. "Oh no!" I hear you bitching; "Not another lecture on music rustling, chair squeaking, and the newfound audibility of overdubbing!" No, that's all old news. All of that goes on—and must, as long as people actually make the music we listen to—but who cares? I'm talking about choices that the artists made about how to make the music—choices that can further inform my relationship to the music, now that I hear them.