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Positive Feedback ISSUE 47
january/february 2010



710 Stereo Amplifier

as reviewed by Marshall Nack







Kharma Exquisite-Midi.

mbl 6010D preamplifier and Soulution 710 stereo amp. ASR Basis Exclusive phono preamp.

VYGER Baltic M turntable, Shelter Harmony cartridge, mbl 1521A transport, mbl 1511F DAC.

Interconnects are Tara Labs The 0.8, Kubala-Sosna Emotion, Audio Note Japan, and Kharma Enigma. Digital cables are Tara Labs The 0.8, Kubala-Sosna Emotion and Audio Note Japan. Speaker wires are TARA Labs The 0.8, Kubala-Sosna Emotion, and Kharma Enigma. AC power cords are Tara Labs The One and Kubala-Sosna Emotion.

TAOC Rack and TITE-35S component footers, Harmonix RFA-78i and Marigo VTS Room Tuning Discs , CORE Designs amp stands, Acoustic System Resonators, Argent Room Lenses, Echo Buster & Sonex acoustic panels, TARA Labs PM/2 and IDAT power conditioners, and Ensemble Mega PowerPoint outlet strips.


Taking Inventory

The task at hand—to evaluate the Soulution 710 Stereo Amplifier—was exhilarating and daunting. It was such a leap from what I'm used to that I found the audiophile lexicon inadequate, Relationships and definitions got turned upside down, even newfangled concepts just beginning to coalesce inside my head were straining under the aural evidence.

Let me count the ways.

the Matter of Intent

In an unprecedented manner, the 710 reproduces intent, an essential part of musical communication. I'm referring to an artist's interpretation of a score.

One of the things musicians must do when they prepare a work is agree on how to play each phrase—to decide on what they want to say and how to say it. Otherwise, you wind up with a cacophony or a mediocrity, because the same half-dozen notes can be articulated umpteen different ways. This is how an artist communicates his distinctive interpretation. It is what makes Gil Shaham's version of the Barber Violin Concerto different from Hilary Hahn's. It is what distinguishes Bernard Haitink's performances from George Szell's.

Intent is captured in the recording session. The question is, does it come out of your speakers—does your system allow you to hear it?

A sure sign that it does is when you find yourself comparing LP after LP. Not how a piano sounds on Decca vs. EMI—that's an engineering artifact. We've all enjoyed observing this, but that's not what I'm talking about here.

Very few components can convey intent. The majority tell the same story, over and over, but the 710 tells many different stories.

Obviously, to be a good storyteller all of the fundamental issues have to be taken care of, the stuff that nine out of ten audiophiles are battling daily. Until these are out of the way, it's not possible to hear this.

To begin with, the amp must have extremely fine low-level resolution. It has to pass along the smallest differences in the signal. That's a given.

Not so obvious, and equally crucial, are neutrality and a light sonic footprint. Up to this point I've never had much regard for these qualities—I've always been rather fond of color in music and, within reason, the more the merrier. The 710 brought the value of these virtues home.

What do we mean by neutrality and what's a sonic footprint? Are they synonymous? Neutral, to me, means: 1) you don't catch a chill or get warm when you put the component in line; 2) frequency response remains flat; 3) tonal balance doesn't get dark or light. Many components meet these criteria.

What's a sonic footprint? Every component has a signature. These are the characteristic colorations and limitations that it imposes over the signal, masking it to a greater or lesser degree.

Interestingly, you can have an amp that sounds neutral but yet has a noticeable footprint. If it makes everything neutral in the same way, it'll tell you the same story over and over again, painting broad strokes over the signal and washing everything with an across-the-board euphony. That's a heavy footprint. It's a sure bet it'll never give you interpretative differences.

The antonym of a heavy footprint is transparency. The term has always seemed a little vague, but I think it refers to the removal of colorations.

In the context of this discussion about intent, you could say the 710 is a highly musical component. If it has a footprint, it is so minimal I can't detect it: thus, it portrays intent more clearly than any component I've come across. This is not to be confused with the oft-understood audio usage where musical means warm, full and forgiving. The 710 is not particularly warm or noticeably full-bodied, and it is certainly not forgiving.

Comparisons to Other Amps

This discussion definitely dwells in the realm of ultra-refined discriminations and components sporting price tags that few in this hobby can spring for. But hang in there 'cause you never know: maybe one day you'll hit the lottery.

Reviewing gear at the highest level of quality presents challenges. It goes without saying that I can only compare the 710 to other amps I know well. At this time, that means two amps obviously not at the 710s price or performance category: the McIntosh Mc501 and my reference mbl 8011 AM monoblocks.

Having just come off a two-month spell with the Mc501s, the memory of this solid-state contender is quite fresh. The McIntosh amps impressed me right from the git-go with a pace-setting cluster of Class A grades, in particular their abundant heft, ample body and extraordinary control over the speakers.

Tonal Balance

The Mc501s control places images in rock-solid locations about the stage, while that amps' voicing lends them extraordinary weight. It's done in such an ingratiating manner that I hesitate to knock the Mc501s on this because they are so much better than most amps. However, ultimately that weight is a problem—it is there even when it shouldn't be. It makes the sound heavy. It is not naturalistic. Even though the Mc501s sound neutral, they have a rather heavy signature. For this reason, they do not make good storytellers, as defined above.

The 710 doesn't carry around excess weight. It shifts tonal balance as befits the instrument playing. This makes it vastly more natural sounding. (The 8011s also fare pretty well on this score.)

Let's discuss bass response for a moment. Through the Mc501s, it was warm, round and quite abundant. Through the mbl 8011s it was less warm and less abundant, and a bit spread out. On the recent McCoy Tyner Quartet release (HalfNote 4533), for example, I couldn't always distinguish the pitch values when Christian McBride took his turn on the upright. (Actually, quite often it's like that in jazz clubs.)

The 710's bass is even tighter than the Mc501s, although not as big, warm and round. It holds that instrument in its own aural space, riding under the other three and doesn't interfere with them. It sure is tuneful. Some might find this closer to an amplified bass. Again, in a live jazz club, the more they amplify the bass, the more the pitch values come out.

Does this compromise overall frequency integration? No, because the double bass has a fully developed overtone structure. I haven't mentioned this yet, but the 710s timbral complexity is as satisfying as a refined tube amp. This is another area where the 710 confounds assumptions about solid-state.

Unlike the Mc501s bass response, which was ever present, there was always a question lurking in the background about its response on top—was it sufficient? There is no such thought concerning the 710. Its treble is remarkably free ranging, reaching upward whenever it needed to. I wasn't conscious of either too much or too little energy, but I was aware of very high purity and even a tad of sweetness. All in all, the top end is pristine. Its quality was never in question.

Except for being extremely clear, the mids didn't register one way of the other. They are issue-free. Overall, the 710s tonal balance is close to the 8011s. Both are lighter than the Mc501s.

Now, in terms of body, close your eyes and conjure up a cylinder, if you would. This is the shape of the Mc501s, with an equal allotment of flesh from top to bottom. They are truly fulsome. The 8011s conjure a pyramid, the top being thinner than the middle, which is again thinner than the bass. The 710s diagram is close to the 8011s, but with a bit more flesh on top. Neither the 8011s nor the 710 have anywhere near the midrange and treble fleshiness of the Mc501s.

What you should gather from the above is that the 710 imparts a frequency response, timbral envelope and an image shape appropriate to the source. It doesn't euphonically beef up the bottom or foreshorten the top. It doesn't strip off or add bloom. The amps' voicing is truly a classy balancing act. Proceed with caution if you start to mess around with it by applying tweaks. Don't disturb what's already excellently done.


Perhaps the most obvious thing is the 710's control: it is unrelenting. While the Mc501s provide several degrees more than my mbl 8011s, they are nowhere near the capability of the 710. For exhibit A, let's look at the 710's transient performance.

Transient Quality

Graphically, you can plot the 710's transient as an ideal square wave. It reacts instantly, and it is the most coherent I've heard. Needless to say, this also applies to the tail end of the note. There are no lagging frequencies, no driver hangover. Some might find it cleans up a little too quickly compared to other amps. This lends the 710 a staccato character.

What happens when you have model transient behavior and you remove lingering frequencies that obscure the tail? It becomes like an X-ray. This can be dangerous, for it leaves any system issues bare-naked. Many component designers intentionally introduce a little smearing to avoid this exposure. If you go with the 710's honest voicing, you better have your issues well in hand.

But the major upside is that rhythmic change-ups are equally exposed and I'm sure they'll bring a smile to your face.

Body and Soul

The Mc501 was very easy to voice. Its strong footprint almost guaranteed it would sound good wherever I put it and whatever wires I used. The same cannot be said for the 710. Its adamant neutrality and minimal footprint make it very particular about its environment. It will not add flesh. It will not sugarcoat your sound—it is too honest for that. It will not fix issues elsewhere in the system.

If you pair the 710 with wires or ancillary gear with an analytical bent, the result could become antiseptic. Be careful you don't turn the 710 into a wallflower.

I started out with a battery of TARA Labs cables, as that's what was on the floor for the Mc501s. With these on the 710, I heard things never encountered before, but it was cold, hard and unforgiving.

My system wasn't ready for this kind of transparency. Now is the time to remind y'all that none of my upstream components are in the same league as the 710. I heard all too clearly their "contributions," so to speak, especially the preamp—this is the first thing I would look to upgrade. My mbl 5011 preamp is one of the best at its price point, but it doesn't complement the 710. It would be replaced with the mbl 6010D, which my sources tell me is a dream matchup. The 6010D is an interesting case. It is an example of a component that is not neutral, being on the warm and colorful side. Yet, in important ways, i.e. resolution, dynamics, and especially timbre, its footprint is minimal. It still meets the criteria to be a good storyteller. (Soulution's own 720 preamp is the likely first choice, but I can't vouch for that until I get it in. Stay tuned.)

On the cable side, swapping over to a full complement of Kubala-Sosna Emotion had a profound impact in terms of humanizing the sound. The K-S added a goodly dose of warmth, body and soul, and proved an excellent match. BTW: the 710 prefers balanced connections.

It's another one of those odd things: in spite of the 710's absolute control, this amp can dance. Because the frequency response is adaptive and not bogged down with excess bass, the treble is quite nimble, and rhythmic change-ups are exposed, the amp has wonderful PRAT.

Power-Related Concerns

Going into this review I was concerned about the 710's power. My speakers are very hungry. They eat watts like nobody's business. In truth, my mbl 8011 AM monoblocks give me excellent sound with the Kharma Exquisite-Midi speakers. But in those musical genres where power is key, they fell quite short of the Mc501s. The specs sum up the difference. The 8011s have 210 watts into 8Ω and 23 amperes of current. The Mc501s have 500 watts into and an incredible 100 amps of current.

My concern was the 710's numbers: 120 watts into 8Ω. Would its peak current of 63 amperes compensate for that low wattage?

Ha! My concern was totally unfounded. The 710 cracked the whip and the Kharma speakers responded with a salute and a click of the heels. Macro dynamics are astonishing, better than I recall when I had the mbl Reference Line 9007s (MSRP $33,400). Are they better than the mbl 9008s (MSRP $50,400)? Don't know these amps well enough to render a verdict. But as impressive as the 710's brute power could be, it was the quality of those dynamics. They were rather like the 710's frequency response: entirely appropriate to the source. There was no unwarranted expansion on the one hand and no sense of inadequacy on the other.

How did the 710 fare with micro-dynamics? This is the 8011's strong point. As I said earlier, I'm hearing things now I've never heard through my reference amps.

It's an old story, but it bears repeating. The system we assemble has everything to do with our musical preferences and vice versa: our musical preferences have a lot to do with what our system is good at. Have you ever noticed that those guys with sweet sounding, tube-based systems tend to listen to chamber music? Those with powerful solid-state systems tend to prefer rock music? Systems tend to be specialists. Now, why is it that few of us reach for the largest-scale symphonic works? The answer in my case has been because the compromises were too great and precluded a satisfying result. You need a heck of a system to playback the big scores satisfyingly.

By now I shouldn't have to mention that the 710 could handle any fare you might throw at it. Anything. (All right, I admit, I didn't try Led Zeppelin.)


Because the Soulution 710 is so revealing, it is a tempting candidate for tweaking. A single Harmonix RF-57 Tuning Base placed above the AC plug had a dramatic impact, in terms of romanticizing the sound. One dot extended decays, let notes ring longer, gave heft to the lower midrange, and generally added liquidity while reigning in the rampaging incisiveness. However, I could also distinctly make out the often hidden downside of these tuning devices—you lose a few overtones and it becomes homogenized.

Setup and Cosmetics

The Soulution 710 chassis is as big as a commercial air conditioning compressor. Viewed from a distance, some called it a Plain Jane box. But close up, the finish exudes luxury and quality. It has a spare, clean look—a Calvin Klein aesthetic.

Given that the 710 weighs 175 lbs, you might be surprised that a well-built stand would matter, but it does. Moving the amp from the carpet onto a TAOC AS-1 amp stand, which happens to have almost perfect dimensions and the same silvery finish, had the same effect as putting any component onto a TAOC rack. The amp stand retails for $750. You will also need the TAOC SP-500 spike set, for another $195. The 710 is very sensitive to its environment.

Don't be surprised if you hear a "pop" from your AC circuit box when you power up the 710. That's the sound of its initial current draw.

Technical Discussion

It's often said about audio circuit design that less is better. You won't get an argument with the idea that fewer parts equate to higher purity. The maxim holds true—up to a point.

So then, what is one to make of a large box that is crammed to the gills with circuitry? There's many times more stuff inside the 710 than any amp I've had the pleasure of poking into.

On top of this, the Soulution importer told me there are all kinds of built-in protections to prevent damage to your speakers or the amp. Doesn't each added protection extract some performance compromise, as it is something else in the signal path?

Current Amp 

Fixed Gain Buffer

Power Supply

Well, I don't hear any compromises, and the protections are real. Once I accidentally switched the line preamp to a source that I had just powered down. Immediately, I heard a loud pop and saw the 710 shut itself down. It came back up again when I changed the preamp selection. I guess it was DC that came through, which could have fried my speakers.


The Soulution 710 solid-state stereo amp delivers your pleasures with fewer compromises than any amp I'm acquainted with. There is nothing to criticize. It doesn't excel in just one or two areas—it achieves SOTA levels in the whole swath of performance criteria.

The only thing I would like to reiterate is the need to choose ancillaries carefully. Between its neutrality and minimal footprint, the 710 is super revealing and will ruthlessly expose any shortcomings or incompatibilities in the chain. It adamantly refuses to sugarcoat the source.

If you are ready for it, the 710 is a stopping point in the same way as my Kharma Exquisite-Midi speakers are. Buy it and your search is over. The net effect of an amp like the 710 is to remove a significant variable from consideration when there's an issue. When I have to hunt down the cause of bad sound, my thoughts won't be directed to the speakers or the amplifier; I look elsewhere.

Postscript: I've decided to take the plunge, my wife has given the green light, and the Soulution 710 will not be returning to the importer. I really had no choice but to grab it. Going back to the mbl 8011s was out of the question. Marshall Nack

710 Stereo Amplifier
Retail: $45,000

Importer information

Axiss Audio, Inc.
Gardena, CA 90248
TEL: 310-329-0187
email address:
web address: