Review by Srajan Ebaen
Power delivery products have become a very, ahem, powerful new audio category. Some might even call it the latest craze or religion. From aftermarket power cords the size of just-fed anacondas to voltage stabilizers with fast-tracking digital displays; from space-heating AC regenerators to tiny passive noise snuffers; from various line conditioners with contrasting filtration techniques to mysterious Quantum devices: music lovers couldn't be blamed for suspecting that without a pert shot of fast-acting Lystenol Antiskeptic [patent pending by yours truly], certain claims in this field might well outweigh actual benefits. In fact, cost of ownership could, at times, seemingly outweigh both claims and benefits. But as is true for all walks of life, every audio category contains winners, losers, the capable main pack, the rare poseur and the occasional real deal. The trick lies in sorting through the propaganda, not losing sight of common sense and accepting that things react differently in different systems. Above all, one should assuredly trust one's own ears.
And my ears tells me that the subject of optimized power delivery for audio systems, rather than an imaginary disease, is truly a much more relevant topic than most music lovers concede. It's worthy of serious attention to getting the very most from our systems. When properly heeded, all its permutations -- including proper grounding and shielding, cable routing and dressing, deoxidizers and contact enhancers -- can create profound effects on the sonic quality of our rigs.
Lord of the Ring
For the last going-on-two years, my personal reference line conditioner has been the Sound Application CF-X, then upgraded to the CF-XE. Its functional but rather industrial appearance, combined with a very significant price tag of $4,200, tends to stimulate the kind of nay-saying or at least doubtful reactions hinted at above. However, its performance puts it squarely at the very top of the heap. In my system, it demolished competitors like MIT's Z-Center, Chang's Lightspeed, Richard Gray's Power Company and PS Audio's PowerPlants. Others have found the CF-X to outperform efforts by Accuphase, Burmester and Goldmund.
Enjoy the Music.com's own Bill Gaw proclaimed the CF-X Component of the Millennium and purchased two for personal use. Senior Editor Dick Olsher, no stranger to state-of-the-art efforts, was equally enthused months earlier. Ultimate Audio's Jerry Kindela later joined this party with yet further confirmations. Coupled with my own findings, it is reasonable to consider this substantial case evidence in favor of the CF-X a kind of universal yardstick against which other line conditioners can be meaningfully compared.
When Audio Magic's Jerry Ramsey offered to send me one of his new Stealth Power Purifiers for evaluation, I jumped at the opportunity. I felt confident that my own long-term experiments with the CF-X had prepared me sufficiently to put any subsequent findings on the Stealth into proper perspective. I had another reason as well. Since my introduction to the Sound Application box, I had often recommended it to inquiring music lovers. I had also recommended it to a few manufacturers as potent weapon against the ubiquitous risk of mediocre sound at trade shows.
According to Jim Saxon's CES 2001 Jimmy Awards, Sound Application arranged to loan their units to at least 28 different exhibits, all of which Saxon felt to have much better than average sound. However, my personal CF-X recommendations -- especially to consumers forking over hard-earned cash rather than enjoying short-term loaners -- were always accompanied by the same kind of inward reaction. I felt compelled to justify the hefty cost against what to the naked eye alone didn't seem like a very commensurate or promising return. But then I also knew the audible benefits of the CF-X to be such that nobody would ever call me back - except to express enthusiasm and gratitude for the often-drastic changes it wrought in their systems. And that's indeed been repeatedly the case.
An Underdog Contender
A question now arose. Could the six-outlet Audio Magic Stealth -- at $1,699 including a silver Xstream power cord less than half the asking price of the CF-X -- seriously claim to perform in the same rarefied league? If it even came close, I'd have to consider it a legitimate option for alternate recommendations, one that incidentally would cause far fewer explanations and justifications about its cost. And that, frankly, was all I really hoped for when I accepted this assignment.
During the ensuing lengthy review period, I also had the opportunity to test a Shunyata Research Hydra, another celebrated genre leader that would further underscore how the Audio Magic Stealth might hold up by comparison. Measuring 10.5" x 3" x 7.5 (WxHxD), the standard Stealth is housed in a black plastic casing. While plain, it actually looks better than the sharp-edged black-anodized aluminum chassis of the CF-X (apparently the latest revision dubbed the XE-12 has revised the case work, which might render this a mute comment) but is left in the dust by the polished granite case, acrylic top and Amaranth wood face of the more expensive Hydra. As Ramsey explained, he also considered going for really fancy cosmetics but opted to save the trick stuff for the insides to keep the costs of the external box work to a minimum. I'm sure other budget-constrained music lovers would join me in calling this a good move.
With its front unadorned save for a tasty blue central power LED, three duplexes, an IEC input and an external circuit breaker on the back panel are where the visible action of the Stealth occurs. The circuit breaker replaces more conventional internal fuses as fast-acting primary protection device. It also passes higher current than the hair's width wire of standard fuses. And then there's the real but invisible action inside the Stealth's case, with another seven stages of secondary surge and spike protection, the firm's trademark ultra-purity 10 gauge silver wiring and five different stages of proprietary broadband noise reduction, one of which I assume is capacitive in nature. While specifics on the exact techniques employed remain guarded - presumably to short-circuit the sincerest form of flattery called intellectual property theft -- the use of Shakti Innovations technology is openly acknowledged. That turns the Stealth into the quintessential Ben & Jerry's audiophile scenario. In fact, Jerry Ramsey is an ardent proponent of Ben Piazza's stones and on-lines. He uses them extensively in his personal system, on his statement Clairvoyant power cords and, for horsepower and handling gains, on the ECUs (engine computer processors) and ignition coils of a Nissan Pathfinder as well as his monstrous Honda Valkyrie 6-cylinder power cruiser (drool).
While a feature review on the Shakti Innovations' stones and on-line filters remains the subject of a future review, I should mention as an introductory aside that a recent and rather vicious string of chat room attacks on inventor Ben Piazza solicited surprise defenses by multiple industry folks. These included John Curl, one of our most decorated solid-state amplifier designers. He had carefully studied Shakti's US patent #5,814,761 and considered it proof positive that Piazza's products are based on rock solid science, never mind that said science could elude detractors and thereby cause offended, offensive and ultimately embarrassing reactions. Billed as electromagnetic stabilizers, the Shakti devices operate passively via proximity effect. At least conceptually -- though implemented with different compounds and circuits - I sense some kind of connection with Shunyata's own proprietary passive filtering and absorption approach. In the case of Shakti Innovations, a three-stage inductive coupling mechanism traps and transforms the parasitic oscillations of radiated fields in the GHz microwave, kHz to MHz radio frequency and 50Hz to 200kHz electric/magnetic frequency ranges via resistively damped inner chambers. For the RF filter stage, a form of quartz crystal acts as the physical energy conversion agent.
Besides the standard Stealth under review, Audio Magic offers two additional units in the Power Purifier series. The two-outlet Mini Stealth ($599 with cord) is recommended for TV/VCR combinations or computer/monitor setups and - for customers wanting to extend its effects without incurring extra costs - can accept a standard power strip in one of its outlets to power more than two components. The tongue-in-cheek christened Stealth B-II ($3,500 with two cords) is a single chassis "double Stealth" with 4 duplexes that are separated into two dual mono banks, each fed from its own power cord, and visually distinguished by two front-mounted VU meters for voltage and current status.
By physically and electrically separating its two circuits, the B-II can effectively isolate digital and analog components. Minus the VU meters, the same could be accomplished with two regular Stealth units - and in financial stages if necessary. I made that comparison in-house and can vouch that both approaches perform indeed identically. Even though I didn't need all of the eight/twelve outlets of either scenario, the physical separation of analog and digital component feeds did offer demonstrable performance gains. Depending on the resolution of your system, your appreciation for ongoing but certainly diminishing returns and the vagaries of system-dependant results, this subject of analog/digital separation makes for potentially very worthwhile experiments.
The Real Deal
To let the cat right out of the bag: the Stealth, challenged as it was by the seriously topnotch company of the Sound Application CF-XE and Shunyata Research Hydra, performed not only competitively but, in my system and according to my personal biases and preferences, in fact walked away victoriously. As we shall see, this statement doesn't at all diminish the capabilities of the others, nor does it exclude the very real possibility that in different systems, and for different listeners, the hierarchy of performance might well get reshuffled. What it does imply is that the least expensive entry of this group performs in the very same elite league as established genre leaders. It further suggests that Audio Magic's diminutive introduction might well be preferable, or at the very least offer a legitimate alternate choice that needs to be included on anyone's short list of final contenders in this class of devices.
During the stay of the Stealth in my system, it benefited from the superior resolution of the dialed-to-the-max Avantgarde Duo 2.2 horn speakers I recently reviewed elsewhere. I used it with Bel Canto Design's eVo 200.4 and Pre1, with my beloved Art Audio PX-25 6wpc single-ended amplifier with volume control, and with the currently-under-review Viva Audio Devices Sintesi SET integrated. Its specific contributions to the overall sound remained stable. This allowed clear differentiation to the other two conditioners.
I live way out in the country, on an open mesa facing the mountains of Northern New Mexico's high desert of Taos. Presumably this means I enjoy less polluted AC delivery than big-city dwellers. Certainly the size of the neighboring two acres single-home lots, and the relative openness of this mesa, means that far fewer households suck on our power grid than they would in condo or track-home land. In fact, the voltage meter of the B-II indicated that while it inhabited my system before moving on to colleague Scott Markwell over at The Abso!ute Sound, the line voltage remained rock-steady at 117V. Regardless, all of the conditioners significantly improved the sound over going straight into the wall. None of them perform voltage correction or stabilization, something most modern power supplies in audio equipment already account for. The cause for their sonic improvements clearly lies in the elimination of noise components and their harmonics that ride atop the 60Hz AC sine wave and create various interference and intermodulation patterns in the audible range.
The first major area of improvement was in perceived resolution - specifically midrange purity, treble sheen and extension, and bass definition, tautness and reach. Here the Stealth caused the most potent gains, with the farthest extended yet balanced and natural highs - especially noteworthy on cymbals, triangles and, yes, upper register pan flutes - and the kind of abysmal trance and ambient bass pulses and foundation pedals that support artificial aural constructs often meant to trigger very primitive and primal emotional reactions in one's body. In bass extension, the CF-X proved a close second. Both devices offered more weight and slam than the Hydra. The Shunyata unit might well have extended as low. Still, by virtue of a comparatively lessened impact, it seemed not to. Conversely, the Hydra shone in the transparency department in a similar way that some electrostatic speakers strike me - very diaphanous, but with transient vividness somewhat toned down when compared to the best dynamic speakers. Personally, I relate much of a sense of live music in the home to how transients and leading edges are reproduced. Live music contains a certain raw edge that's not at all synonymous with the dreaded electronic blade of glare or dynamic compression. Rather, it's a vital function of instruments and vocals coupling directly to the air, unencumbered by interceding electronics that shave off minuscule signal portions. The superior rise times of the horn-loaded transducers of the Avantgarde Duos, combined with how this transfers into ultra precise tracking of micro-dynamic fluctuations, are two of their most endearing attributes to these ears. The Art Audio Jota, very un-SET like, excels in the same domain.
The Stealth, possibly by accentuating or just very accurately resolving this innate musical energy, struck my cochlea in likewise fashion. By contrast and as valid counterpoint, the Hydra smoothed over this "edge of aliveness", sublimating, for example, the ferociousness of rapidly struck guitar strings or the raw bite of blistering brass. Depending on one's preferences, this could either be termed a smoother or more filtered, drier presentation. Another way of hinting at the same difference is to call the Stealth more vital and exciting, the Hydra more relaxed and a mite more subdued. The CF-X, as was generally the case also with other performance aspects, took up the middle position between both poles but straddled closer to the Audio Magic than the Shunyata Research unit. Especially in the midrange, one could perhaps call the CF-X a bit sweeter than the Stealth while certainly not quite as resolved.
Soundstage devotees will enjoy the superior depth perspective of the Stealth that required 200+ hours of break-in to unfold what initially seemed like minor spatial compression. After the requisite preconditioning protocol, its portrayal of soundstage depth struck me as the best of this group and, especially with well-recorded classical music, proved to be a real boon.
The second major area of improvement, rendered to similar degrees by all conditioners, was the extent to which the sonic fabric appeared more intelligible, better defined, with enhanced contrasts and, especially via the Stealth, a broader micro-dynamic envelope in which individual notes first arose out of silence, then bloomed and finally faded into oblivion. For this latter trait, the proverbial "blacker background" simile comes to mind. Exploring it will help to further differentiate a subtle distinction between especially the Stealth and Hydra. Some audiophiles describe the jet-black background of their system as a lifelike quality that contributes much to enhance their system's realism. To my ears, live performances exhibit a potently charged silence, a distinct psychic presence or pressure that is not the same as the mere absence of sound or noise. It is, in a strange way, acutely audible and often described as "silence so thick you could cut it". In this respect, the ephemeral and relaxed presentation of the Hydra struck me as perhaps somewhat damped, arising more against an absence of sound - perhaps a noise vacuum -- rather than this living presence. That was certainly a subtle attribute and should be thought of as related to the wet/dry syndrome of the tubes vs. solid-state debate. Once recognized and conceptualized, it remained clearly repeatable. Preferences, as well they should, will likely vary once again.
Unlike the Hydra, both CF-X and Stealth provide surge and spike protection. A recent midnight thunderstorm had me appreciate this added protection. Lightning hit close enough to my house to jerk me out of deep sleep with the first thought that an airborne missile had struck and exploded - the ground shook, there was a pronounced sense of devastating impact, and the electrical grounding was frighteningly loud. I frankly had never experienced anything this seemingly warlike before - welcome, I flashed, to the unique high-altitude atmospheric conditions of the desert. When I attempted to power up my rig next morning, no response. Since the ceiling lights worked, the main circuit breaker wasn't the culprit - the li'l one on the back of the Stealth was. I held my breath to see whether it would reset. It did. Once the PX-25 tubes stabilized, glorious music as usual. I had been saved from the audiophile version of fry bread, that high and empty calorie treat local American Indians consider tradition. Quite literally, this particular lightning had been a darn close call.
The Audio Magic Stealth technology, according to designer Jerry Ramsey, offers another surprising fringe benefit. It extends the life of any component plugged into it, such as CRTs in TVs and computer screens, vacuum tubes and other hard-working circuit parts. For example, Ramsey owns an air purifier that, in line with the manufacturer's concise usage statement and his prolonged personal experience, cycles through its $100 each ultra-violet light bulbs in 12 months or less. Ever since this air purifier has been plugged into a Stealth power conditioner, the last set of its bulbs is well past 18 months of continuous duty and still shows no sign of giving up its ghost. He offered further case evidence. In his downstairs Dynamic Sound Environments, Ramsey uses a plethora of tube amps to tri-amp his unique planar/dynamic in-wall speaker arrays. He's noted a drastically reduced consumption of power tubes since the electronics have been powered with Stealth technology. These observations make him feel confident that his Stealth technology isn't just good for better sound and pictures, but also good for the components producing them.
A few months ago, Lloyd Walker accompanied Ron Bauman of inSound for a business-cum-pleasure trip to New Mexico and stopped in Taos for an in-house demonstration of his Walker Audio Valid Points resonance control system (review forthcoming. Seemingly eyeing the little Audio Magic Stealth in my system with unguarded suspicion, I obliged Walker who owns a heavily modified CF-XE and otherwise rather mistrusts power line filtration devices. We performed the famous audiophile swapperoo between both units just long enough for him to yank my chain, attempt a rise out of me and laconically suggest I take the CF-X and throw it into the trash. Like me, he much preferred the Stealth in this particular instance. Remaining intensely curious and very much into continuously fine-tuning his system, Walker then called Jerry Ramsey shortly afterwards and ordered a sample Stealth. Experimenting in his own system, he told me that he favored the stock Stealth over his custom CF-XE (from which he removed the magnetic circuit breaker and varistor banks). However, Walker's customary Quantum Products Symphony parallel device, in conjunction with the CF-X, outdid the Stealth, which wasn't as copasetic with the second box. So, Walker continues to use his trusty Sound Application/Quantum Products setup for best results.
Consider this is a much-needed reminder that your personal findings in your own system must, as always, remain the final arbiter in these matters. How a component works in one system may be different from another. Reviews can only help to introduce new components and place them into a certain context that then remains subject to how it applies to your own situation. But, this particular example underscores again how the affordable Stealth, in a very different electrical and physical environment, could more than hold its own against much dearer, heavily modified and daisy-chained competition. In our triumvirate of statement-level devices - Audio Magic Stealth, Shunyata Research Hydra, Sound Application CF-XE - the Stealth's only failing is its relative lack of expense or sex appeal. When you can impress friends with far heftier price tags or designer cosmetics, why brag about this little box for $1,699? That of course is really the greatest compliment I could bestow upon the Audio Magic Stealth, save to add that for now - baring any future groundbreaking discoveries at its price -- this unassuming black box has become my new no-brainer, first-to-mind recommendation for power line conditioners under $5,000.
Power line conditioner with 3 rear-mounted Leviton hospital-grade duplex AC outlets for six individual sockets
Detachable 6-ft Audio Magic Xstream silver-ribbon power cord
External 15-amp circuit breaker
Black plastic casing
Blue front-mounted power LED
Dimensions: 10.5" x 3" x 7.5 (WxHxD)
Price: $1,699 in standard version (includes standard cord)
$599 in mini version (two outlets, includes standard cord)
$3,500 in B-II version (8 outlets, dual mono, two VU meters, includes two standard cords)
$800/1,000 for 1.5/2m optional Power Master power cord
Waranty: 3-year warranty