Phono Preamp Reviews

"Saying that Sutherland Engineering builds a nice line of phono stages is like saying that the Porsche 911 Carrera is a nice line of sports cars." So began my review of Sutherland's PhonoBlock in the January 2012 issue. I went on to note that similar philosophies underpin both product lines, and to link the cost-no-object PhonoBlock ($10,000/pair) with the GT2 RS ($245,000), then the pinnacle of Porsche's 911 family. It's now 2017, and though Sutherland and Porsche have both gone through a complete development cycle and replaced their flagship models, the analogy still holds true.

What makes a Duo a Duo?
A key element of the design of Sutherland's new Duo dual-mono phono preamplifier ($4000 for both chassis) was apparent when its shipping cartons—as in two—arrived on my doorstep: two identical mono units. Ron Sutherland believes that this approach offers a number of advantages over a single box, or two boxes that split up the functions: power supply in one, audio circuits in the other. In an e-mail, he ticked off the advantages:

"There is obviously the elimination of crosstalk . . . and it's much easier to design a mono circuit than a stereo one. Everything is simpler . . . there's more room to optimize the layout, and to do things that make it easier to manufacture, which ends up helping reliability. Both channels see identical electrical and mechanical environments, so you don't have to compromise the performance of one channel to improve the performance of the other. Sometimes doing that can require different parts as well as different layouts. That drives up the cost, so you have to make tradeoffs somewhere else. Beyond a certain point, it costs more to improve the performance of a single-chassis unit than it does to build another chassis."

Once I'd opened the cartons, I saw that the Duos were built into the same small casework used for Sutherland's Insight stereo phono preamplifier, rather than the one used for Sutherland's other mono models. Other than size, the Duos' cases mirror the larger ones. They're built of the same powder-coated, heavy-gauge steel with a faceplate of ½"-thick anodized aluminum, the latter's surface interrupted by only the Sutherland logo at lower left and, at lower right, a single LED to indicate that the unit is powered on.

On each rear panel are one RCA jack for input, another one for output, and a grounding post for a turntable. As with all Sutherland designs save the Argentum Plus, the Duo has no provisions for balanced operation. There's also an IEC receptacle for a power cord, but only a basic AC cord is supplied. Says Sutherland, "Most customers are going to use one they pick, so why add the cost?"

The Duo's internal layout is similar to the PhonoBlock's, with separate subchassis for the power supply and audio circuits, and a single connection between the two. The connection in the considerably more expensive PhonoBlock is elegant: a ribbon cable running inside the faceplate; the Duo's subchassis are instead connected by circuit board labeled Power Bridge. Some may see this as a less elegant approach, but it's way cooler. Not surprisingly, the Duo's circuitry is much less complex than the PhonoBlock's. Rather than the PhonoBlock's linear supply, the Duo's supply is based on the internal switching supply first seen in the Insight.

Loosening four thumbscrews allows the casework cover to be removed, to gain access to the sockets and jumpers used to set the cartridge loading and gain. There are five possible loading values, ranging from 100 to 47k ohms, and the choices of gain level are 40, 46, 52, 58, and 64dB.

Every aspect of the Duo's construction reflects the superb quality seen in other Sutherland models. The boards are sheer engineering artwork, adorned with such audio jewelry as Dale/Vishay 1% metal-film resistors and 1% polystyrene film capacitors, the latter custom-wound to Sutherland's specs. The boards themselves are made of the same ¹/₈"-thick FR-4 fiberglass used in the PhonoBlock, the thicker material being Sutherland's simple, elegant way of eliminating the capacitance created in a typical ¹/₁₆"-thick board bearing circuits on both sides.

The Duo's operation is simple and intuitive, and the two of them worked perfectly during their time with me. As with all Sutherland products, the Duo's conservative design and superb build quality strongly suggest that it will prove bulletproof throughout a long and happy life.

Listening
I began by putting on the Juilliard String Quartet's recording of Schubert's Quartets 12 in c and 14 in d, D703 and D810 (LP, RCA Living Stereo LSC-2378). I sat back and listened. Try as I might to ignore the Duo's sound, by the end of Quartet 12, two things had become obvious: The Duo unquestionably sounded like a Sutherland, and quite a bit different from other Sutherlands I've heard.

The sound had a characteristic that's unique to Sutherland phono preamps while being shared by all of them. The soundstage and the sounds of the musicians' instruments weren't being re-created in my listening room. Rather, they were being revealed—as if the Duos were melting away some opaque, impermeable substance that otherwise encases and obscures the sounds. It felt the way it does when, at a live performance, the first note is sounded.

Most models of audio gear made by the same manufacturer display some sort of audible family resemblance, but in my experience, few such resemblances are as strong as the Sutherlands'—another example of the aptness of the Sutherland/Porsche analogy. Once you've driven a 911 or spent time listening to a Sutherland preamp, there's no mistaking either for anything from any other maker, and in both cases the reason can be traced to a single fundamental design choice. In the case of the 911, it's the use of an anachronistic rear-engine, flat-six layout. With Ron Sutherland, it's his reliance upon passive resistor-capacitor (RC) circuits.

I did most of my serious listening to the Duo by repeating a pattern of three types of listening session: just listening; then, listening and thinking about how the Duo might be affecting the music; and, finally, listening while dissecting and characterizing its sound in terms of specific attributes that travel well among audiophiles.

To follow a path to enlightenment, you must know where you begin.
The first step began that first night, when I dropped the needle on the Juilliard Quartet's Schubert. As more listening sessions ensued, I casually observed my reactions to what I was hearing and considered a few basic questions. Had I been captivated by the performance on the recording I'd just listened to? When it ended, was I disappointed and reluctant to let go? Or had I already chosen the next album I wanted to hear, or even already gotten it out? Did one evening spent listening have me already planning the next? Over time, my observations accumulated, and jelled into an answer to the first basic question: Had I been captivated by the performance on the recording I'd just listened to? My answer was Yes, absolutely.

A path to enlightenment, but is it the right path?
The second question might be: Did the Duo sound right?

Here I followed my second pattern: listening while also thinking about the five basic elements of music: pitch, timing, loudness, timbre, and location. Individually, nothing could be simpler. Combined, nothing could be more complex. Any sort of error or discontinuity, however small, can upset this intricate balance and destroy the magic. At a live performance, it might be a single violin note that's slightly off-key or a half-heartbeat late. At the other end of the chain of performance, recording, and playback, where an audio system sits, everything matters, and it matters more and more as you move upstream.

At the beginning, the interface of record groove and stylus, the need for precise accuracy is absolute. A system can work only with the information it retrieves at this interface. The same is true of a cartridge's tiny coils, magnets, and suspension, where the mechanical signal is transduced into an electrical one. No error that occurs here can be fixed downstream.

The phono preamp is just as critical, and its job is every bit as difficult. Here is where an insanely delicate, microvolt-level signal must be perfectly and significantly manipulated, then amplified by 60dB or more. This must be done across ranges of frequency and volume comprising several orders of magnitude, in a box that provides constantly changing mechanical and electrical environments that are unbelievably hostile to audio signals. Everything that a phono preamp does matters, and it has to get everything right.

The Duo got it right.

Landmarks along the way
My first listening session made it clear that the Duo was a Sutherland phono preamp, largely because of the primal purity of instruments' timbres and the natural, effortless feel of the performers being simply revealed. The Duos' soundstage didn't just end at some clearly marked boundary; it spread to envelop everything within the bounds of the performance space, to create a single, coherent aural environment. When Michael Fremer reviewed Sutherland's PhD phono stage in January 2004, he discussed its vanishingly low noise, and how it gave rise to this purity and an unusually "black" background. He aptly described it as a freedom from "electronic detritus,"—a description that fit the Duo's sound to a T.

Some of the other ways the Duo reproduced spatial information also hewed to the Sutherland family resemblance. One was that it resolved low-level and inner detail past the point where hearing becomes perceiving, and even that becomes increasingly ephemeral. The various ways that a violinist moved his or her finger to create vibrato were one example. It wasn't obvious that they were there with the Duo in the system, but with most other preamps, it was obvious that they weren't.