Soulution 711 Stereo Amplifier, 701 Monoblock Amplifier, and 725 Full-Function Preamplifier
Soulution, the Swiss company with the whimsical name, has been on a genuine tear lately. Its “more affordable” 5 Series electronics—the $55k 501 monoblock amplifier and $26k 520 full-function preamplifier, which I raved about in Issue 235—were in certain key ways (the bottom octaves, timbre, and large-scale dynamics) considerable improvements over its original, far-pricier 7 Series offerings (the $115k 700 monoblocks, the $40k 710 stereo amp, and the $40k 720 preamp, which I also raved about back in Issue 199). Now, with the release of its even more costly second-generation 7 Series components—the $155k 701 monoblocks that Robert will comment on, and the $65k 711 stereo amplifier and the $50k 725 full-function preamplifier that I will discuss—Soulution has put the horse back before the cart, producing what are, by a fair margin, the best solid-state electronics I’ve heard in my system. Indeed, the best electronics I’ve heard period, tube or solid-state.
I’m sorely tempted to leave it at that and save you the ordeal of reading paragraph after paragraph of backstory (and me the trial of writing them), but since claiming something is “the best” is close to meaningless without an explanation of what “the best” signifies, we’ll take the scenic route.
As it’s been a while since I reviewed the original 7 Series product, let me start by going over the ground that sets all Soulution gear apart from other solid-state, tube, and hybrid gear—the company’s unorthodox use of negative feedback.
I first heard about Soulution (the name is a concatenation of “soul” and “solution”) from solid-state amp maven and loudspeaker-designer Alon Wolf back in 2008. At the time I knew nothing about the brand, and when I looked it up on-line and discovered it was owned by another Swiss company called Spemot that specialized in building electrical motors and refrigeration units for the automotive industry, I was not enthralled. Shades of Crown, thought I. Then I chanced upon a rave review of a Soulution product—the 120Wpc dual-mono Soulution 710 stereo amp—in the tough-minded German hi-fi magazine Stereo, and got more interested. You see Stereo had pronounced the 710 a sonic and technological wunderkind. Indeed, the amp had tested so unprecedentedly low in distortion, so high in channel separation, so superbly well in S/N ratio that the magazine’s chief technician hung the test results in a gold frame above his bench.
Of course, some of us (at least some who go back that far) remember those Japanese solid-state amps from Sansui and others that also boasted record-low THD figures—but sounded like crap. The trouble was that to achieve such stellar specs the Japanese engineers had to ladle on so much global negative feedback that their amps were virtual TIM (transient intermodulation distortion) and SID (slew-induced distortion) generators. Feeding back the signal from the output in order to compare it to the signal at the input (and thus fix any errors that may have accrued as it made its way through the circuit) works fine if that feedback process is instantaneous, but feedback is a disaster if the amp takes too long to make its corrections. After all, the musical signal coming into the amplifier doesn’t hold still for a portrait; it is constantly changing; and if too much time elapses (and we’re talking nanoseconds here), the signal that the feedback circuit is comparing at the output is no longer the same signal that is being seen at the input. Think of it as a worst-case “jitter” scenario, albeit in the analog realm. Ever since the “specs wars” of the late Sixties, the received wisdom about solid-state has been that negative feedback is a bad thing—only to be applied sparingly and locally—while shorter signal paths and fewer parts are good ones.
With its 7 Series electronics Soulution turned this conventional thinking on its ear. In concert with the company’s owner and CEO, Cyrill Hammer, Soulution’s engineers decided that it wasn’t feedback itself, but the speed at which the feedback loop operated that was the problem.
As I’ve already noted, to eliminate the time-related distortion, graininess, and edginess that feedback engenders, you have to make those feedback loops correct errors instantaneously. This means that circuits and power supplies must operate at incredibly high speeds (which translates into incredibly high bandwidths) and with very high precision. Forgetting about shorter signal paths and fewer parts (the 710 amplifier used over 3000 components!), Soulution found ways to do this very thing, reducing propagation delay times (the amount of elapsed time it takes to correct a signal via feedback) to 5–10 nanoseconds (billionths of a second), where big solid-state amps typically had propagation delay times of 1–5 microseconds (millionths of a second). This thousand-fold increase in speed allowed for a huge increase in local negative feedback (and a drastic lowering of THD levels), without the usual price paid in time-domain errors.
The measured results of Soulution’s ingenious, high-speed, high-local-feedback circuit were phenomenal. In the 710 stereo amp, for example, THD was well below 0.0006%, signal-to-noise ratio well above 108dB, channel separation an astounding 86dB, damping factor greater than 10,0000, slew rate 330V/ns, while power bandwidth went from DC to 1MHz. (The monoblock amps measured substantially better!)
The sonic results were just as astounding. Suddenly you could hear…everything, and hear it with unprecedented clarity, speed, and neutrality.
I will never forget my first listen to the Soulution 710 stereo amplifier. It just so happened that, at the time, I was using what remains the most finely detailed transducer I’ve reviewed, the then-brand-new MartinLogan CLX electrostats. In concert, that amp and those speakers set a standard of transparency and resolution that had never before been approached and has never since been equaled in my system. The sheer number of previously inaudible details about the performance, the music, the venue, and the engineering they brought to light on record after record—and these were records I thought I knew by heart—was simply mind-boggling.
Hearing exactly how, oh, Joni Mitchell’s vocal harmonies on Blue had been separately recorded in a sound booth and then potted into the mix to create a plethora of Joni’s in the background (backing up Joni in the foreground) simply thrilled a “fidelity-to-sources” listener like me, for whom the experience was like peering over the shoulder of the mastering engineer and observing how he’d mixed the various tracks down to two-channel work parts. However, I could also see where so much “non-musical” detail might be off-putting to a listener for whom the color and drama of music comes first. After all, not everyone wants to watch the man behind the curtain twiddling dials and adjusting sliders each time he sits down to enjoy his favorite tunes.
Indeed for some listeners (not me, mind you) the 710’s presentation was overly “analytical”—dreaded word—in that it revealed artifices (like tape splices, mike preamp clipping, and overdubs, as well as every mechanical noise that a musical instrument is capable of making when it is played close by the diaphragm of a microphone) that other, less transparent amps and preamps glossed over, and that the musicians and recording and mastering engineers probably didn’t want or intend you to hear so plainly. While I reveled in this wealth of detail for all the previously unheard subtleties it revealed and for the greater sense of realism it brought to well-recorded sources, some members of my little listening panel weren’t so sanguine. A few of them felt the 710—particularly in combination with the CLXes—was just a bit too revealing.
Moreover, it could be argued (and was in other mags) that the 710’s super-high resolution was being purchased at a cost in lifelike density of tone color. Even a fan like me would have to admit that listening through it did require a bit of a sonic adjustment. The 710 was not an amp one would ever call warm and inviting—or cold and off-putting, for that matter. It just didn’t have a color of its own; like glass or water it had the color of what you saw through it or reflected by it, be that the source or the speakers. Some critics (and some on my listening panel) chose to view this colorlessness as the absence of tone color, and by tube or tube-hybrid amplifier standards the amp was a bit lean in the all-important midbass and power range (100Hz–400Hz), where so much of music’s drive, body, and natural warmth originate.
My bottom-line conclusion about the 710 was that if you were an “absolute sound” or “fidelity-to-source” listeners like me, it was a no-brainer must-listen. However, if you preferred an inherently warmer, richer, more gemütlich sound, then the 710 probably wouldn’t be your cup of resistors and capacitors.
This is where things stood with Soulution gear until the introduction, in 2012, of the company’s new 5 Series electronics, wherein everything changed—dramatically.
Although I’d previously heard prototype 501 monoblock amplifiers and the 520 preamplifier at several shows around the country and the world, I was not fully prepared for the enormous change in sonic character that these fabulous new electronics brought to the table.
Everything that “as you like it” (or “musicality first”) listeners complained about in the original 7 Series electronics—the overly detailed presentation (that, for some, bordered on the analytical), the leaning out of tone color in the midbass and power range (that, for some, robbed the amp of natural warmth and weight), the “too-neutral-and-transparent” overall sound (that, for some, bordered on sterility)—was gone! In its place were a natural warmth and near-voluptuous beauty of timbre that I’ve seldom before heard in solid-state amplifiers, and a bass and lower midrange power, color, weight, and impact that I’d never heard before from any electronics of any kind.
What the hell happened?
If you read the sidebar interview with Soulution’s CEO, Cyrill Hammer, you will get a detailed answer to that question. But the short-form response is that the new power supplies in the 5 Series amplifiers and preamplifiers (and the consequent changes those PSUs allowed in circuit topology) made all the difference.
Unlike the original 7 Series amplifiers, the 5 Series used “switched-mode” power supplies (SMPS)—two of them, electrically isolated from each other (and from the audio circuit) by opto-couplers and transformers, “high-performance-filtered” for noise at the inputs and outputs, and high-speed voltage-regulated. Each of these switched-mode supplies was capable of delivering 600VA, and Soulution claimed that, together, they “delivered considerably more stable power than any conventional, transformer-based technology.” (Lest you be confused, the Soulution 501 was not a Class D amp. Though it used a switched-mode power supply, its gain stages ran in Class AB, heavily biased toward Class A. In addition to the switched-mode supplies, the 501 also used four linear power supplies for other functions.)
The upside of SMPSes as I understood it (make that “as Robert Harley explained it to me”) is that they keep the power supply’s filter capacitors constantly and fully charged no matter what the signal-demands; they can also be power-factor-corrected (so that current and voltage are not slightly out of phase, as they are in conventional supplies).
As I said in my review of the 5 Series electronics, I was also aware there were switched-mode naysayers, who pointed out that, even if filtered and shielded, the strong noise (chiefly RF) of the digital switching signal could be radiated throughout the circuit. All I can tell you is that I didn’t and don’t hear this issue. (For measured confirmation, see the charts in my interview with Cyrill Hammer.) What I did and do hear is that when an amp has no droop in the supply at any level with any signal, the net effect seems to be equivalent to plugging your speakers directly into a wall socket.
When it comes to dynamic linearity the 501 was simply nonpareil. Every other amp I’d listened to, tube or solid-state, reached a point where it simply couldn’t get louder or more dynamic without also audibly changing its sonic character. Sometimes, this pivot point came relatively early on, as it did with the puny ARC Reference 210 monoblocks (less so with the stouter Reference 250s); sometimes it came relatively late, as it did with the Constellation Centaur. But came it did. And when it came, the music didn’t just get louder (if it did get louder); it also got more distorted. Typically, timbres began to lose their natural sweetness, becoming thinner, more skeletal; with the loss of tone color textural details seemed to be planed away, too, so that the resolution of instrumental body and performer articulations was greatly reduced; transients and big dynamic swings often acquired a sharp, unpleasant edge or, alternately, sounded flattened out, as if they were being compressed against an invisible loudness ceiling; the soundstage, in turn, congealed, as if it, too, were being pressed against a pane of glass. Understand that all of these effects set in well before actual clipping. Understand, as well, that the absence of this sense of strain or compression is one of the foremost differences (if not the foremost difference) between music performed live and music played back on a stereo.
Up until it could give no more and its protection circuits simply shut it down to silence, the 501 was the only amp I’d heard that didn’t do any of this. It just kept getting louder without any change in sonic character—so far beyond what you might expect from its nominal 125 watts that its actual output was difficult to gauge. And because it kept getting louder without strain or outright distortion magical things happened in the bass and power range on big dynamic moments. Tymps, bass drums, gongs, doublebasses, trombones, sarrusophones, tubas, trumpets, bassoons and contrabassoons, bass clarinets, saxophones, pianos, organs acquired the acoustical power that they have in life on big orchestral tuttis—that sense of effortless, seemingly limitless power focused by the hall and projected toward you with enough physical force to be felt like an onrushing wave. With the 501s, bass-range instruments gained sweetness, texture, solidity, and energy as they got louder, as if the amp were continuously kicking itself into higher gears—as if there were no end to the gears it could engage. (The question of how an amplifier performs when it is stressed by musical dynamics, particularly in the bass, and by volume levels is the main reason why I feel that the old saw about the seminal importance of “the first watt” is, at best, misleading. In many—if not most—real-world systems, it is the hundredth watt that counts, and as I just got done saying the hundredth watt rarely sounds anything like the first one.)
When you combined this incredibly lifelike delivery of power, top to bottom, with the 5 Series’ newfound warmth and density of tone color, you got a solid-state amp and preamp the likes of which I’d never before heard. No, I don’t suppose the 501/520 sounded quite as incredibly detailed as Soulution’s 700/720 (or Constellation’s Performance Series products), but, as I said in my review of the Odyssey Stratos monoblocks in our last issue, it is hard to know whether this was an inherent shortcoming (and if it were a shortcoming, it sure wasn’t much of one), or whether the addition of so much more power, color, and weight in the bass and midrange was simply making the upper midrange and treble (where a goodly number of transients live) sound less “exposed.” In any event, a lack of detail was the last thing you’d complain about in a 5 Series product.
True, the tonal balance of the 5 Series amps was now inherently dark, warm, and beauteous—what Michael Børresen of Raidho calls a “bottom-up” sound, far removed from the brook-clear neutrality and colorlessness of the 7 Series offerings. But having spent most of my life listening to warmish tube amplifiers, that didn’t faze me. In fact, after living with the 501 monoblocks and the 520 preamplifier (driving Raidho D-5s and D-1s) for the better part of a year, I would’ve been hard put to imagine electronics that were better, which is to say, more beautiful, more exciting, and more lifelike on everything from violin sonatas to Lou Reed in his glam period. I truly loved the Soulution 5 Series electronics and wouldn’t have traded them for anything else. Indeed, I would still feel that way were it not for the damnable arrival of Soulution’s second-generation 7 Series amp and preamp under review.
As I said at the start of this tome, saying something is “the best” is meaningless if you don’t define the term. So…let me define it now. No, it does not come down to detail or dynamics or imaging or soundstaging or timbre or texture, although all these things play key parts. And, no, it does not come down to the absolute sound, either, although, on well-recorded acoustic music the fool-you semblance of real instruments playing in a real space is essential. At this point in my long, grey career in audio reviewing, I think a thing can only be called “the best” a reviewer has heard if, and only if, he honestly believes that it is likely to fully satisfy every kind of listener on every kind of music in just about any kind of system.
Let’s face it (as I’ve tried to do in review after review), most gear appeals primarily to a certain kind of listener—be he a “fidelity-to-source” or “absolute sound” or “musicality first” one. This doesn’t make such equipment unworthy—far from it—it simply means (if one is honest and objective, rather than biased and absurdly dogmatic about our hobby) that what is perfect for a given listener with a specific taste in sound and music and a certain kind of hi-fi system isn’t necessarily going to be as perfect (or close to as perfect) for another listener with a different taste in sound and music and a different system. This, friends, is the way the world works, ignoring such variables and telling readers what they should prefer (because the reviewer himself prefers such things) is, IMO, propaganda.
Don’t get me wrong: A reviewer must have his own preferences, but he should not let them stand in the way of objectively describing and/or recommending equipment that, while it may not fully meet his own needs, will clearly meet those of someone with a different approach to sound and a different taste in music. I’m not advocating the abandonment of standards (personal or professional), and I’m certainly not saying that there aren’t appreciable differences among audio components, nor am I advocating the kind of test-based absolutism or blind (in more than one sense of the word) listening that results in absurd positions such as: “All amplifiers sound the same,” or “Outside of the way they load sources, cable and interconnects make no sonic difference,” or “The LP is a low-resolution medium.” I’m simply saying that reviewers could do worse than to become a bit more catholic in their approach to what they’re reviewing. I’m also saying that for me, calling something the “best” of its kind means that I can’t imagine a listener who wouldn’t consider the component in question ideally suited to his sonic preferences and musical taste and hi-fi system, no matter what those things happen to be.
Which brings us at long last (I warned you—remember?) to the Soulution 711 stereo amplifier and 725 preamplifier under review. Because the 711 and 725 sound so much alike, I’m going to concentrate on the amplifier—and comment on the preamplifier in a sidebar. You can safely assume, however, that when used together the 711 and the 725 (once broken in) have precisely the same sonic character.
Happily, it is easy to describe both of these products. On the outside, they are identical to their forebears; both are housed in the same gun-metal grey, Bauhaus-style chassis that Soulution used for the 710 amp and 720 preamp, with little rectangular windows inset in their faceplates for their LED readout screens that allow you, via the remote or control knobs on the units themselves, to select various options. Inside, they use the exact same high-speed, high-negative-feedback circuits found in their 7 Series predecessors. As far as the amplification stages are concerned, the 711 is identical to the 710, and the 725 to the 720.
As was the case with the 5 Series components, the big difference in both the amp and the preamp is their power supplies. Like the 501 monoblocks, the 711 dual-mono stereo amplifier uses two, fully regulated switched-mode power supplies (as well as several linear supplies for certain sub-systems), and it uses these SMPSes for the same reasons they were employed in the 501—to keep “the voltage to the amplifier channels perfectly constant irrespective of the music signals.”
As Cyrill Hammer says in the sidebar interview, the use of these SMPSes had certain beneficial side benefits beyond providing cleaner, nearly inexhaustible power. For instance, because an SMPS runs cooler (while permitting it to create higher voltage), Soulution was able to omit noisy cooling fans in the 711. In addition, since SMPSes allow for much more efficient power-factor correction (PFC), the supplies no longer polluted the mains with harmonics and current spikes, as linear supplies do, improving the performance of the amp itself and of ancillary electronics that are also plugged into the wall. Furthermore, the smaller size of the SMPSes allowed a more efficient arrangement of parts and boards inside the amp, reducing the lengths of cable that had to be used between and among them, thus making for shorter signal paths. Finally, when these much more stable and efficient, lower-noise, higher-output SMPSes were paired with 1,000,000 microfarads of custom-made ultra-low-ESR capacitors (as they are in the 711), current peaks, particularly in the bass, could be reproduced with greater ease and fidelity, and current delivery could be raised from 60A to 120A (although pulling that much current out of the wall may prove to be a problem in most homes).
What this translates to sonically is almost exactly the same thing that it translated to in the 501 monoblocks—an amplifier with simply unparalleled bass-range power, color, and impact (even better here than the 501, an amp that I thought couldn’t be bettered in the bottom octaves), a power range and midrange of exceptional warmth and tonal beauty (ditto), and a treble that is as liquid, edgeless, and delicately detailed as any I’ve heard from solid-state. The 711 stereo amplifier is every bit as gorgeous, thrilling dynamic, startlingly lifelike (given the right sources), and seemingly inexhaustible as the superb 501 mono. Indeed, it might be just a shade more inexhaustible (if that isn’t a solecism), in that it doesn’t ultimately give up the ghost and shut down, no matter how loudly you play it. In addition to its inexhaustibility, the 711 has much of the same marvelous (and extremely lifelike) sonic stability of the 5 Series monoblocks—sounding virtually (though perhaps not quite as completely) the same at very low levels as it does at ear-splittingly high ones.
So far I’m describing an amp that has the same virtues as a less expensive one. But the truth is that the 711 has a leg up on the 501 in every area in which the less-pricey amp excels; plus it does certain things more than a leg better that the 501. First, there is the sheer amount of information about performers and performance that the 711 delivers. While the 501 is an extremely detailed amplifier, it’s no Soulution 710 when it comes to low- and high-level resolution. The 711 very nearly is. To hear the effortless way this amp sorts out strings, winds, brass, and percussion (and individual players within each section) even on the most floor-shaking fortississimos of a terrifically busy and dynamic piece like the Feria of Ravel’s Rapsodie espagnol is to hear a huge symphony orchestra reproduced with so much of the limitless ease and air, dense and variegated tone color, and thrilling acoustical power of a real orchestra in a real hall that it will send chills down your spine and goosebumps up your arms. (The Soulution 711 is, if nothing else, a non-stop goosebump-raising machine, regardless of music.)
But the 711 doesn’t just turn this high-resolution trick with big music—be it classical, rock, or jazz. It also has the 710’s ineffable touch when it comes to very low-level textures—the way strings, for instance, are being plucked or brushed or picked, or singers are shepherding their breath or modulating their vibrato. Soulution’s new stereo amp will leave you in no doubt about how a performer is playing his instrument and the mechanism by which the instrument is producing sound. When, for instance, I told you in a previous review about being able to hear how pianist Gilbert Kalish was alternately using his fingernails and the pads of his fingertips to rub the thick coiled strings of his concert grand in the open-piano glissandos of George Crumb’s Four Nocturnes, I was also telling you about the incredibly fine resolution of colors, textures, and articulations that Soulution’s new amplifier and preamplifier are capable of. Of course, the 710 and 720 preamp were capable of this selfsame thing, the difference being that the 711/725 does it while also fully preserving the natural warmth and density of tone color of the instrument Kalish is playing. (The second thing the Soulution 711 is, if nothing else, is meltingly beautiful in timbre.)
Then there are its bass dynamics. As I’ve already noted, I thought the Soulution 501 was unbeatable in the low end. But in all my life I’ve never heard Fender bass lines, kickdrums, and toms reproduced by an amplifier with as much lifelike speed, color, power, authority, and effortless ease as they are through the 711. Listeners have literally come out of their chairs when they’ve heard the tremendous impact of Chris Frantz’s sledgehammer drumming at the end of “Life During Wartime” or Tina Weymouth’s fat, throbbing, incredibly powerful bass line intro to “Take Me To The River” from The Talking Head’s Stop Making Sense. And, as I’ve already noted, the 711 is just as incredibly lifelike on big moments with full orchestra, such as the massive crescendos of Rapsodie espagnol. Trust me here: Outside of an actual rock, big jazz band, or symphonic concert, you’ve never heard anything like this amp in the bottom octaves. Which leads me to the third thing that the Soulution 711 is; if nothing else, it is a benchmark in the bass and power range, capable of unrivaled slam, inexhaustible dynamic range, and ravishing tonal color.
So what doesn’t it do? Well, the 711 isn’t as colorlessly neutral as the 710. Like the 501, it has a big, dark, tremendously authoritative, bottom-up sound. Though not as beguilingly soft in the treble as the 501, it is still probably a bit softer than life in the top octaves (at least when it is driven by the phonostage in Soulution’s companion 725 preamp). While very high in resolution and superb on transients, it is not quite the sonic vacuum cleaner that the original 710 was or that the Technical Brain TBP-Zero/EX is. Though it has an astonishing measure of the three-dimensional bloom that I associate with tube amps (Soulution amps are almost unique among solid-state components in this regard), it doesn’t have quite the same lifelike midband presence of, say, the ARC Reference gear; nor does it have the pitch-perfect steady-state tone that ARC has in the midrange (although ARC simply doesn’t compete with the 711 on transients or at the frequency extremes). When it comes to soundstaging and imaging the 711 is also a bit reminiscent of ARC tube amps, in that the stage is wall-to-wall vast, while instrumental images within that stage are less razor-cut and more life-sized than they are through most other solid-state amplifiers. (Once again, this larger, more natural, more tube-like imaging is characteristic of Soulution.) Finally, because of its tremendous energy—it may sound like I’m exaggerating this quality, but I’m not—and dense, lifelike color from the bottom bass right through the power range, the 711 may drive your speakers and your room a little nuts on certain midbass notes in big tuttis (as I said in my review of the considerably more lightly balanced Odyssey Strati). But once you hear all that horripilating speed and slam and color, you’re not going to care.
As great as the Soulution 711 is, there are other amps out there that may equal or outdo it in this area or that. (The Constellation amps, for instance, are at least as quick and detailed, albeit leaner and less authoritative in the bass range and more top-down sounding; the fabulous Siltech SAGA system is also nearly as high in speed and resolution and at least as beautiful in tone color, although also somewhat top-down in balance and less visceral in impact, at least in comparison to the ultra-authoritative bass octaves of the Soulution; when it comes to vocal realism the ARC amps I mentioned a paragraph ago still rather own the midrange; and the Technical Brain TPB-Zero/EX remains the once and future king of transient speed, ultra-fine detail, and colorless neutrality—the perfect amp for “transparency-to-source” listeners.) Still, IMO, none of these very worthy competitors has quite the same universal appeal—the potential to please every kind of listener on every kind of music in virtually every kind of system (save perhaps for horns)—that I feel the Soulution 7 Series gear has. This is an amp (and preamp) with enough resolution to consistently delight a fidelity to sources listener like me, enough fool-ya realism (on realistic recordings) to make absolute sound listeners swoon, and more than enough beauty and dynamism to knock it out of the park for those of you for whom the power and passion of music come first. Trust me again, folks: Once you hear the 711 you’ll want to own it. If you can’t afford it (and how many of us can?) there is always the next-best 501/520 combo for less (albeit still a lot of) money, the high-res Constellation Performance Series at about the same price, the uniquely beguiling Siltech SAGA hybrid, the ultra-transparent Technical Brain, or, for a lot less dough, the phenomenal Odyssey Stratos monoblocks.
It goes without saying that the Soulution 711 gets my highest, warmest, and most enthusiastic recommendation, as does its companion preamplifier the 725 (for which see the sidebar). Once again, it is the most consistently beautiful, thrillingly dynamic, and persuasively lifelike amplifier I’ve heard in my system thus far, no matter the music or the source. It is also, in case you haven’t yet noticed, the winner of The Absolute Sound’s highest honor, our 2014 Overall Product of the Year Award (which it shares with its monoblock cousins and its companion-piece, the superb Soulution 725 preamplifier).
SPECS & PRICING
Type: Stereo solid-state power amplifier
Power rating: 2 x 150W @ 8 ohms; 2 x 300W @ 4 ohms; 2 x 600W @ 2 ohms
Output voltage max: 31V RMS
Output current max: 120A
Impulse power rating: >6000W
Sensitivity: 1.55V RMS
Frequency response: DC–1MHz
Slew rate: 400V/ns
THD+N @ 1kHz: <0.001%
Signal to noise ratio: >108dB
Damping factor: >10,000
Input impedance: XLR, 4.7k ohms; RCA, 10k ohms
Output impedance: 0.001 ohms
Dimensions: 277mm x 480mm x 277mm
Weight: 143 lbs.
Type: Full-function solid-state preamplifier
Amplification: Balanced, +9.5–18.5dB; unbalanced, +3.5–12.5dB; phono, +54–60dB
Frequency response: DC–1MHz
Slew rate: 400V/ns
Distortion (THD): <0.0006%
Signal-to-noise ratio: 130dB
Input impedance: Balanced, 2k ohms; unbalanced, 47k ohms; phono, adjustable
Output impedance: Balanced 2 ohms; unbalanced, 2 ohms; record, 100 ohms
Inputs: Two balanced (XLR); three unbalanced (RCA); one phono (RCA)
Outputs: One balanced (XLR); one unbalanced (RCA); two LINK-System (RJ45); one DC-Out (sub-D high current)
Dimensions: 480mm x 167mm x 450mm
Weight: 66 lbs.
JV’s Reference System
Loudspeakers: Raidho D-5, Raidho D-1, Avantgarde Zero 1, MartinLogan CLX, Magnepan 1.7, Magnepan 3.7, Magnepan 20.7
Linestage preamps: Soulution 725, Constellation Virgo, Audio Research Reference 10, Siltech SAGA System C1, Zanden 3100
Phonostage preamps: Audio Research Corporation Reference Phono 10, Constellation Audio Perseus, Innovative Cohesion Engineering Raptor, Soulution 725, Zanden 120
Power amplifiers: Soulution 711, Siltech SAGA System V1/P1, Constellation Centaur, Audio Research Reference 250, Lamm ML2.2, Zanden 8120, Odyssey Audio Stratos
Analog source: Walker Audio Proscenium Black Diamond Mk V, TW Acustic Black Knight, AMG Viella 12
Tape deck: United Home Audio UHA-Q Phase 11 OPS
Phono cartridges: Clearaudio Goldfinger Statement, Ortofon MC Anna, Ortofon MC A90, Benz LP S-MR
Digital source: Berkeley Alpha DAC 2
Cable and interconnect: Crystal Cable Absolute Dream, Synergistic Research Galileo LE, Ansuz Acoustics Diamond
Power cords: Crystal Cable Absolute Dream, Synergistic Research Galileo LE, Ansuz Acoustics Diamond
Power conditioner: Synergistic Research Galileo LE, Technical Brain
Accessories: Synergistic ART and HFT/FEQ system, Shakti Hallographs (6), Zanden room treatment, A/V Room Services Metu panels and traps, ASC Tube Traps, Critical Mass MAXXUM equipment and amp stands, 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
By Jonathan Valin
I’ve been a creative writer for most of life. Throughout the 80s and 90s, I wrote eleven novels and many stories—some of which were nominated for (and won) prizes, one of which was made into a not-very-good movie by Paramount, and all of which are still available hardbound and via download on Amazon. At the same time I taught creative writing at a couple of universities and worked brief stints in Hollywood. It looked as if teaching and writing more novels, stories, reviews, and scripts was going to be my life. Then HP called me up out of the blue, and everything changed. I’ve told this story several times, but it’s worth repeating because the second half of my life hinged on it. I’d been an audiophile since I was in my mid-teens, and did all the things a young audiophile did back then, buying what I could afford (mainly on the used market), hanging with audiophile friends almost exclusively, and poring over J. Gordon Holt’s Stereophile and Harry Pearson’s Absolute Sound. Come the early 90s, I took a year and a half off from writing my next novel and, music lover that I was, researched and wrote a book (now out of print) about my favorite classical records on the RCA label. Somehow Harry found out about that book (The RCA Bible), got my phone number (which was unlisted, so to this day I don’t know how he unearthed it), and called. Since I’d been reading him since I was a kid, I was shocked. “I feel like I’m talking to God,” I told him. “No,” said he, in that deep rumbling voice of his, “God is talking to you.” I laughed, of course. But in a way it worked out to be true, since from almost that moment forward I’ve devoted my life to writing about audio and music—first for Harry at TAS, then for Fi (the magazine I founded alongside Wayne Garcia), and in the new millennium at TAS again, when HP hired me back after Fi folded. It’s been an odd and, for the most part, serendipitous career, in which things have simply come my way, like Harry’s phone call, without me planning for them. For better and worse I’ve just gone with them on instinct and my talent to spin words, which is as close to being musical as I come.More articles from this editor
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