Vincent Audio SA-31MK Hybrid Linestage Preamplifier & SP-331MK Hybrid Power Amplifier (TAS 208)

Equipment report
Solid-state power amplifiers
Vincent Audio SA 31MK Hybrid Linestage,
Vincent Audio SP 331MK Hybrid Power
Vincent Audio SA-31MK Hybrid Linestage Preamplifier & SP-331MK Hybrid Power Amplifier (TAS 208)

Audiophilia is a strange, often frustrating, yet occasionally euphoric state that, as was determined many years ago by an eminent Freudian (a fan, if I’m not mistaken, of 845-based vacuum tube amplifiers), almost always affects the male population.

But as it is with collecting Swiss watches or rare wines, driving a fine automobile, or tracking down genuine Cuban cigars, this hobby ain’t exactly cheap. It can also lead to a state known as Audiopihila Nervosa, which can wreak havoc on both one’s psyche and paycheck. (To gauge your status, take The Audiophilia Nervosa Test at

As certain pages of this magazine can attest, for the true audiophile, the type of guy who burns through gear faster than Tiger Woods can shout, “Fore!,” there is plenty of state-of-the-art equipment to buy (and sell) while questing for the Holy Grail. And even for those of us who can’t afford the latest and greatest, these rare birds—the Walkers, Wilsons, Magicos, and Solutions, to name but a few—not only define what’s achievable at the leading edge of our hobby; they also, like the Maltese Falcon, are the stuff that dreams are made of.

To be sure, there are many fine examples of value-oriented gear out there. Components that deliver a lot of musical pleasure at a price the average schlub can afford (as a matter of fact, that’s the entire purpose of this column). For guys like that, like me, my suggestion is to stop chasing the Holy Grail, pour a shot of single malt (a relatively affordable indulgence), sit back, and enjoy the music.

Which is something, I can report, that the newest gear from Vincent Audio allows for quite handily.

The SA-31MK linestage preamp and SP-331MK power amplifier are both hybrid designs, aiming to marry the reliability, speed, and power of solid-state with the warmth, air, and harmonic richness of tubes. Both are upgraded editions of the SA-31 and SP-331 that Chris Martens was so high on by back in Issue 173. And while those models remain in Vincent’s lineup—at $649 and $1299 respectively—the new MK versions aim to build on the sonic qualities of their predecessors while still offering strong value-for-dollar.

At $1399, the SA-31MK linestage features a new output circuit with shorter signal paths, and adds a second set of 6N16 vacuum tubes to the original pair found in the SA-31. The new model is also said to incorporate higher-grade, European-sourced resistors and capacitors, electronic volume and input controls, two more sets of line inputs, plus a brushed-aluminum remote control (a feature Chris lamented the lack of when he reviewed the SA-31).

Like its predecessor, the SA-31MK offers a few, somewhat retro features that seem aimed at the buyer who may be stepping up to his first set of separates from an integrated amplifier or receiver: One is bass and treble controls that can be activated or deactivated via a front-panel button; the other is a LOUD(ness) switch to goose up the sound at lower listening levels. (Both remained unused during my evaluation sessions.)

At $2199, SP-331MK specs out with the same power rating as its MK-less brother—150Wpc into 8 ohms, and 300Wpc into 4 ohms—but unlike that unit is designed to operate in a pure Class A mode for up to 10 watts of output power. The Vincent team’s reasoning is, “When listening to music at moderate sound levels, the power reaching the loudspeakers is typically less than 1 watt, and for serious audiophiles seeking to parse the finest details of a musical performance a pure Class A amplifier is preferred.” This is true enough in theory, but my experience driving a notoriously power-hungry speaker like the Magnepan 1.7 leads me to think of the SP-331MK as a slightly dual-natured beast (more on this shortly).

Other differences between the two amplifiers reside in the MK-edition’s new 12AU7 “tube stabilized” Class A power supply, which is coupled to a large toroidal transformer. Its 80,0000µF per channel of storage capacitance helps the amp to double its output power from eight- to four-ohm loads.

Finally, the MK model offers two sets of five-way binding posts, allowing for the addition of a second pair of speakers. Front panel SPEAKER A and SPEAKER B switches allow one to select either or both pairs. This again seems a nod to listeners who may not quite be prepared for the lack of such flexibility found on most higher-end separates.

The Vincent pair is quite similarly voiced, but I’ll start by describing the sound of the amplifier, which, as I already hinted at, does change character as it morphs from its moderately powerful Class A mode into full-on-powerhouse Class AB operation.

A Mahler symphony is a classic example of music where the often—and frequently abrupt—swings of dynamic scaling will demand that an amplifier shift from one power extreme to another in the blink of an eye. If the amplifier were a car, this would be like meandering along in first gear at ten miles per hour before jamming directly into fifth gear and 120 mph. Mahler being Mahler, he usually begins gently and ramps up to near peaks after shifting through most musical gears several times, before eventually unleashing the orchestra’s full muscle—sometimes for relatively extended periods, but just as often within the kind of extreme speed described above. The demands on an amplifier—not to mention the musicians—are highly taxing. And not all amps retain the same sonic signature when driven to such extremes.

On Bernstein’s reading of the Symphony No. 4 [Columbia], the SP-331MK was impressively spacious at the start of the first movement, opening up a convincingly lifelike and well-defined soundstage, with a satisfying sense of air between the players. The musical ebb and flow were likewise very good, with a fine feeling of lilt and pace. Tonally the amp is well balanced, leaning to the darker side of the scale, and it delivers a nice feeling of instrumental texture—silky strings, jangling sleigh bells, skeletal harps, full-throated brass—as well as decent body and bloom (the impression of air expanding and contracting with instrumental volume).

But during later passages, when Mahler’s orchestration takes flight, the SP-331MK starts to pinch a bit. Its tonality grows noticeably grayer, strings become a bit ragged, bloom tightens, and the amp sounds less comfortable, not quite as solid of footing. Well aware that Maggie 1.7s can also become uncomfortable sounding when pushed too far, I was careful to cross-reference what I heard with other music, as well as with the (admittedly much more costly) Cary SLP 05 linestage preamplifier CAD-211 FE amplifiers reviewed in our September issue.

Let me also be clear about this: While I’m describing a character change I believe this amp undergoes as a result, I am guessing, of its switch from Class A to AB operation, I also think this is an otherwise pretty terrific design that, despite its high power rating, may simply be happier when not pushed all the way to its power limit.

For instance, Harmonia Mundi’s superb Gershwin By Grofé CD gave similar results when driven too hard. But when kept to more reasonable volumes, this beautifully recorded disc, with a rich color palette, wonderful spaciousness, and a walloping bottom end, allowed the SP-331 to shine.

And when Abbey Lincoln sings “Strong Man,” from That’s Him! [Riverside/OJC], the Vincent delivered her warm, beautifully breathy performance with great expressiveness, a solidly well-defined rhythm section, and the burly tenor playing of Sonny Rollins. The SP-331MK was clearly in “cruise” mode, and it made for a very involving listening experience (as well as a bittersweet one, since I’d just heard the news of Lincoln’s death).

On Berg’s Lyric Suite, as played by the Ramor Quartet on the Turnabout label, the SP-331MK effortlessly allowed individual instrumental threads to speak on their own as well as with the ensemble. Micro-dynamic shading was also good; the amp delivered fine clarity during almost whisper-soft, muted moments, as well as during energetic pizzicato passages. The quartet evinced both top-end sweetness as well as an angularity of attack throughout Berg’s tightly woven masterwork.

As noted, the sonic nature of SA-31MK is quite similar to that of the SP-331MK. It too leans a bit to the mellow side of the tonal spectrum, and adds a consistent if fine layer of texture to the sound. This isn’t necessarily a bad thing, depending on the music. It can bring an extra bit of texture to a violin or cello, or, with a record such as Lightnin’ Hopkins’ Goin’ Away [Analogue Productions/ Bluesville], add a bit of gritty warmth and sassy presence to a tune such as “Wake Up Old Lady.”

Staging and focus are both strengths of these Vincent designs. Be it small ensembles or large, the amp and preamp convincingly recreate the atmosphere of the venue, with a tightly locked focus on instruments. In this regard I believe the amp is a bit superior, as in my experience the SA-31MK doesn’t have quite the air or bloom the amp has.

Eric Dolphy’s Out To Lunch [Music Matters/Blue Note] showed that the SA-31MK, like the SP-331MK, is quite good with pace, rhythm and attack. “Hat and Beard,” a composition Dolphy attributed to Monk’s influence, begins with an insistently repeated eight-note theme stated by the rhythm section of Richard Davis (bass), Tony Williams (drums), and Bobby Hutcherson (vibes). The Vincent pair nailed the staccato theme, with its forcefully accented final note, but just as easily allowed for Dolphy’s warm, slightly wooly bass clarinet to then fly about as freely as jazz can.

Like all Vincent gear, these units are available in either silver or black finishes, and their affordability is made possible by Chinese manufacturing. And affordability was exactly what Vincent founder, an electronics engineer named Uwe Bartel, had in mind when he started the company in 1995.

So, no, Vincent’s SA-31Mk and SP-331MK are not perfect (surprise—and what is?), and are therefore unlikely to cure Audiophilia Nervosa. Of course, nothing will, least of all reading about gear in reviews such as this one. What might is our acceptance of the facts that audiophilia is a hobby that’s supposed to be fun, and that there is always going to be a guy out there with a system that’s “better” than ours. And as much as I advocate a music-first approach, I’m not above my own lust for new toys. It’s nice to find ones like these that deliver so much pleasure for such a relatively modest price.


SA 31MK Hybrid Linestage Preamp
Inputs: 6 pairs RCA
Outputs: 2 pairs RCA, 1 tape out (RCA)
Tube complement: 4 x 6N16
Dimensions: 17” x 3.75” x 14.5”
Weight: 18 lbs.
Price: $1399

SP 331MK Hybrid Power Amplifier
Power output: 150Wpc into 8 ohms; 300Wpc into 4 ohms (10Wpc into 8 ohms Class A)
Number and type of inputs: 1 pair RCA
Number and type of outputs: 2 pairs of 5-way binding posts
Tube complement: 2 x 6N16, 1 x 12AU7
Dimensions: 17” x 7.75” x 15.75”
Weight: 48.5 lbs.
Price: $2199

3427 Kraft Street South East
Grand Rapids, Michigan 49512
(616) 885.9809

TW-Acustic Raven One turntable; Tri-Planar Ultimate VII arm; Benz Gullwing moving-coil cartridge; Simaudio CD-1 compact disc player; Artemis Labs PL-1 phonostage; Cary Audio SLP 05 linestage preamplifier & CAD-211 FE monoblock amplifiers;
Magnepan MG 1.7 loudspeakers; Tara Labs Zero interconnects, Omega speaker cables, The One power cords, and BP-10B Power Screen; Finite Elemente Spider equipment racks