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Equipment Review
April 2003

Audio Magic Stealth and Stealth Mini Digital Power Conditioners

by John Potis

"What the Audio Magic Stealth and Stealth Mini Digital brought to my system cannot be overstated." 

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Review Summary
Sound With the Stealth, "bass had new authority" -- " a meaty vividness and three-dimensionality about it that was amazing"; there was "also now a sense of expansive space that was completely new"; "Stealth Mini Digital wasn’t quite as consequential to the sound of my system as the original Stealth, but what it contributed must still be deemed significant."
Features Stealth: "nondescript" six-outlet power conditioner that features "10-gauge solid-silver wiring…, five distinct stages of broadband noise reduction…, and seven stages of surge and spike protection"; Stealth Mini Digital: two outlets and "special circuit designed specifically for digital components."
Use The Stealth is meant for use with preamps, power amps, and analog equipment; as its name implies, the Stealth Mini Digital is for digital components -- a maximum of two.
Value "I can think of no upgrade other than buying a new pair of speakers that could come close to making the same impact on an audio system."

When I get e-mail asking about power cords and power conditioners, I’m usually forced to stop short of blanket recommendations. The fact is that no two audio systems may suffer exactly the same performance-inhibiting power-related maladies, so what performs miracles in one system may or may not do the same in the next. If you don’t suffer what a particular product is designed to fix , then chances are that the product will be of little value to you. It’s like taking an aspirin when you don’t have a headache and then pronouncing it the equivalent to snake oil when it seems to do nothing for you. On the other hand, if you do suffer in a serious way from what the product is designed to cure, that product could be a Godsend -- and no manner of hyperbole used to describe the transformation of your system would seem too exaggerated or excessive.

My house

My home sits in a very large valley that seems to exact a strange toll when it comes to the efficient dissipation of radio waves and other forms of electronic interference. It could be used as a lab of sorts because of its saturation with RFI. Some years ago I arrived home from work and dropped myself into my listening chair in time to enjoy the last half hour of the Rush Limbaugh radio program. The problem was that I didn’t have a tuner in my system, and the amplifiers were turned off. At the listening chair, I was treated to 60dBs of Rush emanating from the powered-subwoofer section of a pair of speakers I was reviewing. A call to the speaker’s manufacturer resulted in three or four visits from the company’s engineers in order to suppress the interference of a local AM station. At any time of day, I can still pick up a telephone on the second floor and listen to AM radio on the handset.

In other words, I have problems, although I haven't always realized they existed. For years it never occurred to me that what I heard from my telephone’s handset could be interfering with the enjoyment of music. Then one day following a discussion with Marc Mickelson on the value of power cords, Marc sent me an assortment of cords to try in my system. After years of reading manufacturer propaganda that almost seemed to invite skepticism, I reluctantly installed the cords in my system. I was dumbstruck by the difference they made, and I’ve been a believer ever since.

Eventually Marc wanted the power cords back (drat!), but there was no going back for me. I needed to find a permanent remedy for my system. I did some checking around and found that some people whose ears I trust were excited about Audio Magic's Stealth power purifier. I was promptly put in contact with Audio Magic’s Jerry Ramsey, who sent me a Stealth for appraisal.

I remember being fairly unimpressed after removing the Stealth from its box. It is completely encased in a 10 1/4"W x 3 1/2"H x 7 1/2"D plastic housing of nondescript aesthetics, the front panel is embossed with silver lettering spelling out the brand and model designation, and it is finished off with a small cobalt-blue LED. But around back the Stealth starts to look like it means business. The rear panel contains an IEC receptacle (I suppose one can always experiment with power cords between the wall and Stealth), a 20-amp circuit breaker, and no less than three Leviton hospital-grade duplex power outlets, for a total of six receptacles.

Opening up the $1699 USD Stealth is a no-no. Audio Magic is pretty close-mouthed about what's going on inside. They do profess to using 10-gauge solid-silver wiring as well as five distinct stages of broadband noise reduction. But Audio Magic didn’t stop there. They went one step further and installed seven stages of surge and spike protection, which I didn’t get the opportunity to report on -- fortunately.

My system

I introduced the Audio Magic Stealth to my system slowly. I first plugged my Herron Audio VTSP-1A preamplifier in and gave a listen. Well, this is the part where no amount of hyperbole would seem to overstate the Stealth’s effect. First, bass had new authority that I had never observed in this system before. Sure, there was new extension and heft, but there was also a meaty vividness and three-dimensionality about it that was amazing. While the sound of an upright bass still seemed to emanate from a single location -- albeit a more highly focused one than before -- it spread like rings on a pond throughout the room with incredible dimensionality and energy.

And soundstaging? Only those cursed with poor vision will fully appreciate the newfound clarity that comes with a new eyeglass prescription -- until that person experiences the same thing in his audio system using the Audio Magic Stealth, that is. There was also now a sense of expansive space that was completely new. Not only was the soundstage more expansive, it was filled with air and a much greater sense of depth than ever before. It is no exaggeration to say that I was hearing my system as I never had before.

Associated Equipment

Loudspeakers – Silverline Sonata II.

Preamplifier Herron Audio VTSP-1A.

Power amplifier – Herron Audio M150 monoblocks.

Digital – Pioneer DV-525 DVD player/Bel Canto DAC 1.1 combination.

Digital cable – DH Labs D-75.

Interconnects – JPS Labs Ultra Conductor.

Speaker cables – JPS Labs Ultra Conductor.

Accessories – Vibrapod isolation footers.

Next I added my Herron M150 mono power amplifiers to the Stealth, and this is when things got interesting. Immediately I noticed that all of the new qualities I’ve mentioned became intensified. Bass, soundstaging, image specificity, air, dimensionality -- they all improved even more. Coincidentally, this very same evening I received an e-mail from Keith Herron asking for my M150s back. Although we had not spoken, he was writing to tell me that he wanted to modify the amplifiers in order to make them more resistant to the effects of radio-frequency interference. I took the opportunity to tell him of the effects of the Audio Magic Stealth, and his only reply was, "Send me back the amps. I think you will be very pleased."

Well, to make a long story short, I returned the amps, and when I received them back, they were completely immune to the magic of the Stealth. In fact, they now sounded without the Stealth exactly as I had remembered them to sound with the Stealth. This is an illustration of what I mean by "what performs miracles in one system may or may not do the same in the next." My amps were now somehow doing what the Stealth had done previously.

Well, next it was time to introduce the digital components to the Stealth. Dutifully and unsuspectingly, I now plugged the Bel Canto DAC2 digital-to-analog converter and the Pioneer DV-535 DVD player (used as transport) into the Stealth and, once more, sat down for a listen. I was horrified. All the improvements I had observed previously were gone. Air? Gone. Dimensionality? Gone. Bass authority? Gone. My system now sounded positively constipated by comparison, and the reduction of perceived space and air induced an uncomfortable sense of claustrophobia.

It was then that I remembered reading it was unwise to allow analog and digital components to share exactly the same power source. An e-mail exchange with Jerry Ramsey confirmed that this was indeed the case -- and the reason for Audio Magic’s Stealth Mini Digital.

The Stealth goes digital

Eventually an Audio Magic Stealth Mini Digital arrived at my door. Sharing all the same cosmetic cues but for a new red faceplate, the Mini Digital Stealth appeared to be just a smaller (6"W x 2 1/2"H x 6 1/2"D) version of the original, although it is said to contain a special circuit designed specifically for digital components. There was the same IEC receptacle, 12-gauge silver wiring, 15-amp breaker, and single 20-amp duplex outlet to serve two components. The Digital Stealth also carried a smaller price tag of $799.

In my system the Stealth Mini Digital produced less dramatic results. This is not to say that the differences wrought by the Stealth Mini Digital are insignificant. No way. But I would judge them of a magnitude one would encounter when comparing two DACs. Given the ear’s propensity to unceremoniously accept improvements in a system and its ruthless ability to throw into sharp relief those differences once removed, the easiest way to tell what the Stealth Mini Digital was doing was to remove it from the system. After months of use, when it came time to put words down on paper, this is what I did.

At first I thought that the Stealth Mini Digital was actually of dubious worth in my system. Things were certainly different without it, but once removed things didn’t seem worse. Yes, there was a slight loss of bloom, and the sound was a touch drier. By way of illustration, I can point to the phenomenon that most have experienced when increasing a preamp's volume. The entire picture blossoms and expands. The soundstage becomes at once larger, more expansive, and more vivid. This is exactly what both Stealths create -- but with no change in the volume, of course. Removing the Stealth Mini Digital had the effect of tucking the soundstage in just a bit at the extremes and settling image placement backward just a touch -- a not unpleasant effect, just different. At first things seemed to be a bit neater and tidier. Quickly I noticed not just a receding stage front, but also a foreshortening stage depth. Image delineation was also lessened, and within a minute or two I noticed on cuts like "Growing Up" from Peter Gabriel’s Up [Geffen 0694933882] less "tidy" placements of instruments before me. Not only were image outlines less distinct, but they were also placed more two-dimensionally on the stage, making for a more vague presentation.

"Pavlov’s Bell" from Aimee Mann’s Lost In Space [SuperEgo Records SE-007] evidenced an added layer of grain without the Stealth Mini Digital and just a touch of new opacity. It was also lacking a significant degree of harmonic richness that previously had lent tonal colors an added measure of density and body. As usual, the soundstage was more two-dimensional by comparison too. Bass also lost a degree of heft, speed, drive, and therefore authenticity.

Things took a giant step backward once I removed the original Stealth from the system and went au natural. Music now sounded like a colored-pencil sketch by comparison: flat and two-dimensional with tonal colors now way too washed out to be believable. Brooks Williams’ Little Lion [Signature Sounds SIC 1255] and its array of acoustic guitars now sounded as though it was a completely different CD. Guitars sounded dryer and flatter. Gone was the palpable sound and richness of tone that had previously made this disc sound so marvelous. Where before the guitars would be located in real space, they now sounded like projections on a wall. The whole tonal balance shifted slightly toward the treble, as the sound became more shrill and instrumental voices were thrown off. It was as if years of tonal maturity were stripped from the guitars. "Joyful Joyful," like the rest of the CD, consists of only guitars with no accompanying instruments or percussion. The incidental muted sounds of the pick on the bass strings along with a little slapping of the guitar body act as a percussion section of sorts and propel the song forward. Even this aspect of the sound was now changed for the worse, as the incidental strikes lost weight and realism and began to sound more like an unintended consequence and less a desired element.

Going back to Peter Gabriel’s Up was another ear-opener. It sounded as though I was listening to a completely remastered (for the worse) CD. Where previously "Darkness" saturated the room with deep bass energy, launching the music’s quintessence throughout the room, it was now distinctly anemic-sounding and completely restrained behind the speakers. Bass was positively prissy by comparison, and it was as though someone had disabled one of the dual 10" woofers in my Silverline Sonata II loudspeakers. Bass extension was curtailed, and where the entire room previously came alive with energy, it now stood eerily at rest. "Growing Up" features Gabriel’s voice moving from center to the extreme right and left and demonstrated that the system had not lost the ability to image well in the lateral plane. However, as the soundstage had basically collapsed at the extremes of the stage, those vocals would seem to appear out of nowhere -- out of a darkened stage, as it were. It just didn’t make sense. The deep bass line did manage to resonate through the room, but now it was distinctly less taught, resonant, and lacking in real punch.

I usually like to crank the volume on this CD. I like to let it seep into every nook and cranny throughout the room and not only energize but saturate it in a way that few rock CDs can. But with the Stealth out of my system, rather than inundating, Up remained a wall of sound at the front of my room. Rather than becoming more involving as volume increased, the sound became abrasive and annoying. It was as though the entire essence of what Gabriel was trying to achieve had been lost.


As I write this, the Audio Magic Stealth has been in my system for well over a year and the Digital Stealth for about four months. Though the Stealth proved of little consequence to my Herron M150 amplifiers, it has proved of greater service to most of the amplifiers I’ve had through here over the course of the last year -- both tube and solid state alike. But no component has reacted as strongly to the Stealth as my preamplifier. The Stealth Mini Digital wasn’t quite as consequential to the sound of my system as the original Stealth, but what it contributed must still be deemed significant. What the Audio Magic Stealth and Stealth Mini Digital brought to my system cannot be overstated. I can think of no upgrade other than buying a new pair of speakers that could come close to making the same impact on an audio system -- and none so cost effective.

I’d like to say that the Stealth preserved the basic character of my system and only made it better, but I can’t. It did much more than that, as it absolutely transformed the sound of my system into something else -- something better. Over the course of the last year I’d grown to take what the Stealth was doing for granted. When for the purpose of this review I removed both Stealths from my system, I was genuinely taken aback by what I heard in the way of total system decline. It will be under severe protest that I ever remove them again.

...John Potis

Audio Magic Stealth and Stealth Mini Digital Power Conditioners
Prices: Stealth: $1699 USD; Stealth Mini Digital: $799.
Warranty: Five years parts and labor.

Audio Magic, Inc.
18063 E. Gunnison Place
Aurora, Colorado 80017
Phone: (888) 464-8202
Fax: (303) 873-7277

E- mail: info@audio-magic.com
Website: www.audio-magic.com

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