Phono Preamp Reviews

Sutherland Engineering's Ron Sutherland has been building highly respected conventional RC-type phono stages since the first settlements at Jericho. But in 2018, on the urging of a friend, he developed a current-drive/transimpedance phono stage and thought it was crazy-good, so he called it the Phono Loco. As I recall, the Phono Loco arrived to a fanfare of praise and curiosity, but it cost a lot ($8200), and a lot of audiophiles were skeptical about its unusual (but not unprecedented) current-mode operation and its need for balanced tonearm leads. This latter condition was a deal-breaker for many (including me) who struggled to comprehend the benefits of current-drive and were already invested in and satisfied with voltage-amplifying phono stages and step-up transformers.

According to the Sutherland Engineering website, the Phono Loco, the less expensive Little Loco ($3800), and the least expensive TZ Vibe ($1400) are best suited for use with low-output, low-internal-impedance moving coil cartridges; high-impedance moving magnet cartridges are not recommended.

Brian Damkroger reviewed the first version of Sutherland's Little Loco in the October 2019 issue of Stereophile. Like the Phono Loco, the Little Loco required fully balanced wiring from the phono cartridge to the Loco's balanced-only XLR inputs. Happily for me, and maybe lucky for you, the new "Mk2" version has only single-ended inputs; it still works only with MC cartridges—the lower the output, the better—but now with no special wiring requirements. This flexibility should clear the path for more audiophiles to explore this alternative preamplification strategy.

Before I asked Mr. Sutherland for a Mk2 review sample, one of my cartridge-whisperer friends had already purchased a Little Loco and was raving about its "relaxed, nonelectronic" sound. He said it was "putting up a strong fight" against his John Curl–designed Vendetta Research SCP-2A, which he has been using continuously since 1990. That's high praise.

When I removed the Little Loco's top plate, the artist and amp-builder in me was impressed with the well-turned-out chassis and master-level circuit board design. Everyone knows how I feel about small power transformers and cheap, wave-soldered green-boards floating in mostly vacant bling-boxes; the Little Loco comes in a sturdy black steel box with an austere, brushed-aluminum faceplate with nothing on the front but a modest logo and a tiny Power On light. Inside, the orange and puce circuit boards are thick and properly hand-soldered.

Ron Sutherland describes the first stage of the Little Loco as a "transimpedance amplifier." A transimpedance amplifier is a current-to-voltage converter whose "gain" is directly proportional to the value (in ohms) of the feedback resistor connecting the output to the inverting input of an op-amp with its noninverting input shorted to ground. The output voltage of this transimpedance amplifier is equal to its input current multiplied by the designer-selected value (in ohms) of its feedback resistor (footnote 1). Ignoring a cartridge's—er—potential for voltage output while maximizing its current output (into a load resistance that is smaller than its own internal impedance) appears to solve the cartridge-loading issue.

The question for today is, how does the sound character of a transimpedance phono stage compare to that of a traditional voltage-gain phono stage and to that of a step-up transformer?

In the 1970s, my "I'm-cooler-than-my-friends" attitude led to my desire to own only British pressings of British-invasion music. After a score of years, that desire led to a need to hear British music on British labels played through British-made hi-fi. This weird, Veblen-esque desire led me down some un-Herb-like musical paths including this old-school audiophile chestnut from the Lyrita catalog: a trio of Walter Leigh compositions played by the London Philharmonic conducted by Trevor Pinnock (Lyrita LP SRCS 126). I've been playing this disc for decades, but I never play it for its musical content, which is forthright and benign to a fault (like the painting reproduced on its green-tinted cover); I use it to determine if my phono cartridge is "navigating the grooves" properly. If I can enjoy listening to both sides in one session, it means the stylus-rock is sitting just right in the LP's slot.

The day I installed Sutherland Engineering's Little Loco Mk2, I played that Leigh-Lyrita recording twice. Both sides. The sounds from this famous disc flowed from my DeVore Fidelity Orangutan O/93 speakers with creamy ease, delicacy of detail, and no spatial congestion. Sutherland's Loco presented the Leigh-Lyrita's delicate air and dramatic spatial layering as dominant features. I could "see" the sturdy, morphing forms of its spatial constructions as I washed dishes in the next room. Also obvious from the next room was the solidity and focus of the Loco's bass octaves. The Koetsu Rosewood Signature Platinum–Loco combo reproduced bass and space with more "obviousness" than my reference, John Curl–designed Parasound Halo JC 3+ phono stage.

Realizing that the Little Loco Mk2 had something special going on, I tried a record I only play for the excitements of its musical content: Cheap Thrills by Big Brother & the Holding Company (Columbia LP KCS 9700). In contrast to those audiophile-approved Walter Leigh creations, this record is "Approved by Hell's Angels – Frisco"; it says so right on its R. Crumb–painted cover. You know you got it/If it makes you feel good.

With the Koetsu's 5 ohm impedance driving the Little Loco, this super-iconic album sounded more like Janis circa 1968 and less like a slightly annoying, heavily doctored Columbia studio album, which is what it usually sounds like. The added crowd noise was obvious but less annoying than usual. With the Loco, the only genuinely live part—Janis singing "Ball and Chain" at the Winterland ballroom—made it through my system with all its strutting wow and mind-altering Thrills intact.

While they cost about the same, Sutherland Engineering's Little Loco and Parasound's $3000 JC 3+ phono preamp are not in direct competition. The JC 3+ is a fully adjustable phono preamplifier that works equally well with any moving coil, moving magnet, or moving iron phono cartridge (footnote 2). The Little Loco's transimpedance input makes it more of a specialist product. Its raison d'être is to make some (perhaps many) moving coil cartridges sound more appealing than they would or could with a conventional voltage-amplifying stage like the Parasound.

During my leisurely back-and-forth comparisons, I noticed that the Little Loco preserved greater and denser amounts of low-level atmospheric information. Images were thicker and more three-dimensional. With the Loco, the back areas of the projected soundspace were filled with more "stuff" to examine. But that's just audiophile fluff-talk. What made the Loco "crazy good" was how it wrangled every ounce of dynamic mojo out of every recording. The Little Loco's easy-flowing dance'n'sing talents made the JC 3+ sound staid and ministerial.

Naturally, current-mode phono stages partner well with low-resistance cartridge coils because they generate less voltage but also resist current less. I enjoy low-impedance moving coils because the reduced mass of their fewer-turns coils recovers more small-signal spatial and atmospheric information than their heavier, more-coil-turns counterparts. (Those counterparts, though, trade some nuance and air for greater drama and dynamics.)

A perfect example of a low-impedance, low–moving mass cartridge is the $6995 My Sonic Lab Ultra Eminent Ex, which I described in Gramophone Dreams #25. The Ultra Ex is my behind-the-scenes music-listening favorite because in my system, it recovers more of what I imagine is in the grooves than the Koetsu does. I've said this repeatedly: My Sonic Lab's Ultra Eminent Ex reaches so far into all-analog black discs that I can hear the magnetic tape passing over the recorder's heads.

According to the Ultra Eminent Ex's designer, Y. Matsudaira, My Sonic Lab's signature SH-µX magnetic core material allows him to make cartridges with minimal coil-turns while still generating a reasonable, 0.3mV output. As a side effect, the Ultra Ex's low-turns coils permit an unusually low 0.6 ohms internal impedance, which should make it a perfect match for the Little Loco.

When I reviewed the Ex, I used the My Sonic Lab's Y. Matsudaira–designed Stage 1030 step-up transformer. Since then, I've used the Ex with a variety of high-quality SUTs and several transistor phono stages loaded at every setting between 14 ohms (with the HoloAudio LCR-1) to 400 ohms (with the Parasound JC 3+); none of these options sounded as right and satisfying as the Stage 1030.

But now, with the Ultra Eminent Ex driving Sutherland Engineering's Little Loco, I never want to change cartridges or phono preamplification again. These two phono products seem made for each other. The Little Loco makes the Ex's quiet spaces quieter, its deep spaces deeper and easier to see into. Transimpedance loading seems to enhance the palpability of the Ultra Eminent Ex's output. When playing orchestral music, the Ex–Loco combo emphasizes the physical character of instruments, the materiality of wood and metal. Rich inner details, like the tautness of drum-head skins or the decay of cymbals, are not submerged in the larger mass of orchestra and hall sounds.

Where does this remarkable current-sucking device fit into the larger schemes of audiophile-quality phonography? If you are committed to high-output moving magnet/moving iron cartridges, it doesn't fit in at all. However, if you are a well-seasoned audiophile that's getting bored with that expensive low-impedance moving coil you once thought was purity and excitement personified, you might reconsider how to amplify its output. At their best, active tube or JFET head amps add an aura of Tesla-lab electric-shock excitement to the output of moving coils. Many are the times I've switched from a JFET head amp to an expensive step-up transformer and been disappointed by the loss of those arm-hair–raising excitements.

But more frequent are the times when I've switched from passive SUT gain to active head-amp gain and been disturbed by the loss of the SUT's radiant, understated, low-fatigue naturalness. But now my months-long auditions of Sutherland Engineering's Little Loco transimpedance phono amplifier indicate that it might give jaded phonophiles the best of JFETs and SUTs. Without the disappointments. Highly recommended.—Herb Reichert

Footnote 2: Although some certain moving iron cartridges work best loaded at about 10k ohms, a rare setting not found on the JC 3+.