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Soulution 755 Phono Preamplifier

This has been a very good year for phonostages chez Valin. Over the past twelve months or so I’ve had the opportunity to audition four outstanding units: the Audio Consulting Silver Rock, the Constellation Perseus, the VAC Statement, and the primary subject of this review, the Soulution 755. Although I could happily live with any of them, no two sound alike. While there are folks on our staff who would be dismayed by such sonic variety, I relish it. But then I’m not as doctrinaire as some. The world is filled with different kinds of listeners and different kinds of music; the absolute sound is filled with different vantages and points of interest; there is, in short, no single canonically “right” presentation.

If, for instance, you are a fidelity-to-sources kind of listener, you will probably gravitate to the $35k Audio Consulting Silver Rock or the $32k Constellation Perseus, both of which have extremely high resolution of musical and engineering detail (thanks in part to very low noise floors). Though there are TAS writers who believe (quite correctly) that such ultra-high detail is something we generally don’t hear in a live concert, I’ve always felt that is rather beside the point. On LP, CD, SACD, DSD, reel-to-reel tape, or whatever, we’re not listening to a live performance—we’re listening to a recorded one, in which the recording process is part and parcel of the presentation. On something like Analogue Productions’ superb LP Dream with Dean, for example, we ought to hear the slight upper-midrange emphasis of the very closely positioned Neumann U-47 microphone used to pick up Deano’s voice; we ought to hear the way it clarifies and occasionally exaggerates sibilants, breath control, and aspects of enunciation (or mispronunciation, in Dean’s case).

The irony is that while such artifacts make Dean sound more recorded, they also make him sound more “there,” precisely because the component qualities of his singing style are being more minutely observed. It seems to me that the preservation of such fine aural detail goes a long way toward making up for The Big Blank Spot at the heart of every recording (which is also the biggest perceptual difference between hearing someone live and hearing someone canned)—our inability to see the musician performing. By giving the listening ear and mind more information than it would ordinarily take in at a live concert, a high-resolution component is also reducing the size of that Big Blank Spot; it is turning sound into a substitute for vision, allowing listeners (in a well-worn phrase) to “almost see” the performer.

In the midband, the essentially passive (one active solid-state device in an interstage-transformer-coupled circuit), battery-powered Audio Consulting is superb at this. Coupled with CH Precision’s L1 linestage and M1 monoblock amplifiers, it reproduces something like Dean’s voice with a level of “you can almost see him” realism that has only been equaled in my experience by the Technical Brain TBC-Zero/TMC-Zero. There is a transparent purity about the Silver Rock—a direct connection to performers and performance—that really sets the unit apart from the other competitors. Of the units in this survey, it is my second favorite—and my alternative reference.

This is not to say that the Audio Consulting is without flaws. While it is not one-dimensionally “flat” sounding (it does have a touch of bloom, mostly in a forward direction), the Silver Rock is not as 3-D as the VAC Statement or Soulution 755, both of which we will come to in a bit. It is also a touch thin through the power range and the bass, giving it a slightly leanish, “top-down” tonal character (once again with CH Precision’s linestage and amplifiers, which are also slightly lean and top-down).

Inherently warmer and fuller in timbre than the Audio Consulting preamp, the Constellation Perseus extends the Silver Rock’s “you can almost see him” resolution to the frequency extremes. Its preservation of detail is so high, its bandwidth so extended, and its soundstaging so panoramic, it can even turn an old chestnut like The Weavers Reunion at Carnegie Hall 1963 [Analogue Productions] into a brand-new listening experience. In large ensemble numbers, such as the stirring finales “Goodnight Irene” and “’Round the World,” the Perseus reproduces every singer, every instrument, every foot tap, every pluck on banjo, guitar, or bass fiddle, every voice joining The Weavers from the Carnegie Hall audience with crystalline clarity. Though this album has always been deeply moving to me for its end-of-era idealism—the hope that “one union can unite us” was already more pipedream than possibility in 1963 (or today)—the sound of all those singers and all those concertgoers briefly united in song has never affected me more powerfully than it did through the Constellation Perseus (and the Constellation Altair II linestage preamplifier and Hercules II Stereo amplifier), simply because of the heightened sense of “many” joining together as “one.” All recordings and electronics should serve music this well.

Once again, the Constellation is not perfect. Though balanced slightly toward the warm side, incredibly clear and fast on transients top to bottom, and plenty hard-hitting in the low bass, it doesn’t have quite the same jaw-dropping resolution in the midband as the Audio Consulting Silver Rock, or the three-dimensional bloom of the VAC, or the density of color and power of the Soulution 755 in the all-important power range. In addition, it is not quite as liquid as some of the other preamps being discussed, with a touch of fine solid-state grain that the other three units don’t have.

I’ve already talked at length about Kevin Hayes’ $80k VAC Statement Phono Stage (and its companion VAC Statement Line Stage) in Issue 263. This is the only tube unit in the group, and, as noted in my review, it has a fair measure of the lifelike timbre and texture of Golden Age tube gear. What it doesn’t have are the noise and coloration that also came with those Golden Age tube classics. Indeed, the VAC Statement Phono Stage (along with its companion Reference Line Stage) is the lowest noise/highest-resolution tube preamp I’ve yet heard.

In the paragraph devoted to the Audio Consulting Silver Rock, I talked about the way in which components with ultra-high resolution can compensate for the Big Blank Spot in our perception of artists on records—our inability to see the performers, to watch them play and coordinate what they are doing with how they sing and sound. The VAC Phono Stage introduces an attribute that makes musicians that much more “almost-see-them” real: three-dimensional bloom.

 

I’m not going to reprint the charts (from John Eargle’s great book Music, Sound, and Technology) that I used in my review of the VAC Statement gear in Issue 263, but the point I made there remains the same: In life and on disc, instruments do not image in a single flat plane; they have volume, body, directionality, and dimensionality that changes with changes in register, timbre, and dynamic. The addition of this third dimension, combined with its near-solid-state like speed and resolution, and richer and more saturated tonal palette, brings the VAC Statement Phono even closer to the absolute sound without any sacrifice in fidelity to sources (indeed, in my view, with an increase in fidelity to sources).

Yet again, the VAC is not perfect. It falls a bit short in the power range and the low bass, where (because of inherent limitations in current delivery) it simply can’t supply all the transient speed and dynamic impact of something like the Constellation Perseus, or the dense color and astonishing grip of the Soulution 755.

Speaking of which.

Like the Constellation Perseus (which was designed by John Curl and Peter Madnick) and the Swiss-made Audio Consulting Silver Rock, the Soulution 755 is a solid-state phono preamp. And there, folks, the similarities—technical and sonic—end.

Like all Soulution electronics (see my interview with Soulution’s Managing Director Cyrill Hammer, who also happens to have designed the 755), the 755 uses very high speed, very high bandwidth (into the megahertz range) circuitry. (Speed and bandwidth are the same thing in this context.) Soulution doesn’t do this because it expects its components to be called on to reproduce a 2MHz tone; it does it because it wants to make negative feedback work as it should.

As you all know, negative feedback has a bad rep. Some amps (tube and solid-state) dispense with it entirely (at a substantial cost in THD). Cyrill Hammer and the other engineers of Soulution have taken a different approach. It is their view that NFB has gotten a bad rep because it has been improperly applied. To make feedback, which compares the output signal to the input signal in order to correct errors, work properly, it must occur instantaneously. Otherwise, the input signal will have changed with the passage of time, and you will be comparing an apple at the output stage to an orange at the input. Very high bandwidth (which, as noted, translates to very high speed) allows Soulution to compare apples to apples. All Soulution components reduce propagation delay (the time it takes to make corrections) from the typical-for-solid-state 1–5 microseconds to 1–2 nanoseconds (one thousand times faster). The result is standard-settingly low distortion levels in preamps and amps that, unlike some, don’t give up the ghost and go into runaway distortion precisely when you hit their rated power limits.

Thanks to Soulution’s circuitry, the 755 is, in fact, a marvel of low distortion, with a noise floor of -140dB (quite phenomenal in a phonostage). Of course, the 755 isn’t just a phonostage. Unlike every other preamp considered in this review, the 755 is a stand-alone phono-preamp. Like those dedicated preamps with built-in DACs that are so popular today (one of which, the 760, Soulution also makes), the 755 is a phonostage and a linestage. Its large chassis houses a highly linear phono equalizer circuit (with a gain of 78dB) and the exact same output circuitry, highly sophisticated PGA (programmable gain amplifier) volume control, and power supply (with more than 500,000 microFarads of capacitance!) found in Soulution’s 725 linestage preamplifier.

The long and the short of this is simple: If you listen to LPs exclusively, the 755, which is able to accommodate up to three phono sources at the same time (two moving coil and one moving magnet), allows you to play back your vinyl with complete control of level and balance. At $72,000, the unit is quite expensive, yes. But you can go directly from it to your power amp (or, since it has two analog outputs, to your power amp and your subwoofer) without degrading the signal by connecting to a separate linestage through a pricey pair of interconnects. (I can tell you from experience that going directly to amplifiers from the 755 is a big sonic step up compared to going from phonostage to linestage to amplifiers, though the 755 can also be used as a traditional phonostage in a system that includes digital sources.)

As for the way it sounds, well, if you take the extraordinary midband resolution of the Audio Consulting Silver Rock, the top-to-bottom transient speed, detail, and soundstaging prowess of the Constellation Perseus, and the bloom, color, and dimensionality of the VAC Statement Phono, then add the most solid power range and powerful low bass you’ve heard from a phonostage preamplifier, you’ve got something like the 755.

 

Whether it’s because of their successful implementation of NFB or their very short signal paths or their dual-mono configuration or their virtually unlimited power supplies, Soulution components have always done several things better than the other solid-state and tube units I’ve reviewed. First, they have the kind of three-dimensional imaging that you generally only hear with valves. Second, they have an incredibly hard-hitting bottom octave. Third, they have an extraordinary power range that adds lifelike foundation and color to the midband and makes the transition to the low bass more continuous (albeit at the price of a somewhat “bottom-up” tonal balance).

When connected directly to an amplifier, the 755 does all three of these things, making it the most realistic-sounding phonostage of the lot. It not only fills in the Big Blank Spot by offering superb resolution, lifelike bloom, three dimensionality, dense tone color, lightning transient speed, and wall-to-wall soundstaging in a single package—making it appealing to fidelity-to-source and absolute sound listeners alike—it also has the midbass slam, low-bass extension and grip, and power range fullness that musicality-first listeners adore. I must say that I haven’t heard anything else quite like it.

Take a listen, for example, to The Band’s “King Harvest (Has Surely Come)” on the outstanding MoFi reissue of The Band. This fabulous ballad, with its hard-knock mix of calamity, endurance, and salvation, has something of the same vibe as The Weavers’ “Union Miners.” Using the sparest of musical means—the tapping of Levon Helm’s cymbal and the climactic thud of kickdrum and bass in the chorus, the swirl of Garth Hudson’s organ (evocative of the sound of the wind on the water), the autumnal dry-leaf crackle of Robbie Robertson’s guitar (the polar opposite of “guitar-hero” pyrotechnics), the clean, rope-like lines of Rick Danko’s Fender, and Helm and Richard Manuel’s hesitant, troubled delivery of the almost imagistic lyrics (“Scarecrow and a yellow moon. Pretty soon the carnival on the edge of town”)—“King Harvest” is a masterpiece of composition, performance, and, in the MFSL reissue, sound. But you won’t get the mysterious, almost overwhelmingly powerful effect of this great song without hearing the way these musical means work individually and together to create the dark, almost Biblical landscape of plague and fervently hoped-for (but not quite certain) redemption.

The Soulution 755 (in combination with the Soulution 711 amplifier) delivers the muscular ache and beauty of “King Harvest” better than I’ve ever before heard it delivered. It is simply magical to hear Helm sitting beside his drums and cymbals in three dimensions—you can almost see him cocking his head and scrunching up his face toward the microphone. To hear Danko’s Fender bass sound not just incredibly dense in color, but ropelike in texture—thick, rounded, there. (Bass strings just don’t get reproduced with this kind of three-dimensionality without a sacrifice in speed, color, and definition.) To hear Robbie Robertson’s elliptical guitar work (about which he wrote: “This was the new way of dealing with the guitar for me, this very subtle playing, leaving out a lot of stuff and just waiting until the last second and then playing the thing in the nick of time”) with its lightning-flash-in-the-clouds suddenness and luminosity intact.

Like the other three preamps in this review, the Soulution 755 is not perfect. As noted, it tends to be a little dark or “bottom-up” sounding (because of the fullness of its power range and bass). It is not as nakedly detailed as something like the Audio Consulting Silver Rock or the Constellation Perseus, but that is because it is incorporating detail into a three-dimensional image rather than delivering everything “upfront” in a single plane. When you listen to it closely, you’ll find next-to-nothing is being omitted. It is also ungodly expensive. But given that it can drive an amplifier directly—obviating the need to purchase a linestage and a pair of expensive interconnects—some of that price tag seems more reasonable, especially given its superb sonics.

As I said at the start I could easily live with all four of these phonostages, but were I forced to choose one for the long haul, the Soulution 755 would be my pick. It is not only the most complete-sounding phono-preamp I’ve yet heard; it is also, in my opinion, the single best product Soulution has thus far made and marketed. It goes without saying, or should, that it gets my highest, most enthusiastic, and most affectionate recommendation. Why affectionate? Because I love the thing. 

Specs & Pricing

Analog inputs: Two unbalanced moving coil; one unbalanced moving magnet
Analog outputs: One balanced output (XLR); one unbalanced output (RCA)
LINK-system: Two RJ45
Gain: 62dB (moving magnet); 78dB (moving coil)
Output voltage: 4Vrms balanced; 2Vrms unbalanced
Peak output current: 1A
Impedance: 10 ohms balanced; 10 ohms unbalanced
Frequency response: DC–2MHz
Total harmonic distortion (THD+N): <0.002%
Noise floor: -140dB 
Price: $72,000

AXISS AUDIO (U.S. Distributor)
17800 South Main Street, Suite 109
Gardena, CA 90248
(310) 329-0187
axissaudio.com

JV’s Reference System
Loudspeakers: Magico M Project, Raidho D-5.1, Raidho D-1, Avantgarde Zero 1, MartinLogan CLX, Magnepan .7, Magnepan 1.7, Magnepan 3.7, Magnepan 20.7
Subwoofers: JL Audio Gotham (pair), Magico QSub 15 (pair), JL Audio CR-1 active crossover
Linestage preamps: Soulution 725, CH Precision L1, Constellation Audio Altair II, Audio Research Reference 10, Siltech SAGA System C1, VAC Statement
Phonostage preamps: Soulution 755, Constellation Audio Perseus, Audio Consulting Silver Rock Toroidal, VAC Statement Phono, Innovative Cohesion Engineering Raptor
Power amplifiers: Soulution 711, CH Precision M1, Constellation Audio Hercules II Stereo, Zanden Audio Systems Model 9600, Air Tight ATM-2001, VAC 450iQ, Siltech SAGA System V1/P1, Odyssey Audio Stratos
Analog sources: Acoustic Signature Invictus/T-9000, Walker Audio Proscenium Black Diamond Mk V, TW Acustic Black Knight, Continuum Audio Labs Obsidian with Viper tonearm, AMG Viella 12
Tape deck: United Home Audio UHA-Q Ultimate OPS
Phono cartridges: Clearaudio Goldfinger Statement, Air Tight Opus-1, Ortofon MC Anna, Ortofon MC A90
Digital source: Berkeley Alpha DAC 2
Cables and interconnects: Crystal Cable Absolute Dream, Synergistic Research Galileo UEF, Ansuz Acoustics Diamond
Power cords: Crystal Cable Absolute Dream, Synergistic Research Galileo UEF, Ansuz Acoustics Diamond
Power conditioner: Synergistic Research Galileo LE, Technical Brain
Support systems: Critical Mass Systems MAXXUM and QXK equipment racks and amp stands
Room treatments: Stein Music H2 Harmonizer System, Synergistic Research UEF Acoustic Panels and UEF Acoustic Dots and ART System, Shakti Hallographs (6), Zanden Acoustic panels, A/V Room Services Metu acoustic panels and traps, ASC Tube Traps
Accessories: Symposium Isis and Ultra equipment platforms, Symposium Rollerblocks and Fat Padz, Walker Prologue Reference equipment and amp stands, Walker Valid Points and Resonance Control discs, Clearaudio Double Matrix SE record cleaner, Synergistic Research RED Quantum fuses, HiFi-Tuning silver/gold fuses

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