TESTED: Running Springs Audio Dmitri AC Power Conditioner

Equipment report
AC conditioners
Running Springs Audio Dmitri AC Power Conditioner
TESTED: Running Springs Audio Dmitri AC Power Conditioner

AC power-conditioning specialist Running Springs Audio has quietly established itself in many first-rate retailers and upper-end systems over the past eight years. Although it has not received as much attention as some others in the category, the company behind Running Springs Audio has long been a pillar of the high end. There’s a good chance that some of the capacitors, transformers, or inductors in your preamplifier, power amplifier, phonostage, AC conditioner, or digital source were made by RTI Electronics, the parent company of Running Springs Audio. In addition to manufacturing transformers and inductors, RTI makes the Teflon, Mylar, metalized polypropylene, and oil capacitors found in some extremely prestigious components.

Running Springs Audio was established to bring finished products to the market, specifically AC-power-conditioning devices. The company enjoys several advantages by virtue of its association with the large parent electronics-manufacturing company. First, RSA has the resources to develop proprietary capacitor and inductor designs specifically for audio-system power conditioning. More than 90% of the parts inside the RSA conditioners are made in house. Second, RSA has access to a highly advanced technical laboratory that’s focused on capacitor and inductor development and testing. Third, the assemblers building RSA conditioners routinely work on electronics that go into NASA, military, and medical applications; the factory is ISO 9001:2000 certified. Fourth, building the components in house allows RSA tighter control over component quality. Finally, RSA claims that in-house component-manufacturing allows it to use a quality of parts that would be prohibitive in other similarly priced products.

The company makes five AC conditioners ranging from the $1699 1800W Haley to the ten-outlet, 2400W, $4499 Dmitri reviewed here. (The conditioners are named after musicians—Jaco and Duke for examples. I presume the Dimitri is named for Shostakovich.) Each of the Dmitri’s outlets is individually isolated from the others, and all are identical—there are no “amplifier” or “digital” blocks of outlets. All the products in the line feature the same parts quality, including platinum-foil capacitors hand-trimmed to achieve 1% tolerances. They also share a proprietary inductor developed specifically for audio-system AC conditioning. This inductor features a special synthetic matrix, around which the coil is hand-wound. This synthetic compound reportedly provides better performance than iron- or air-core inductors. The internal wiring is Cardas. Incidentally, the conditioners work with 110V or 220V AC power without reconfiguring.

The Dmitri is available with a stock AC cord (20-amp connector) for $4495; the Dmitri and a Running Springs Audio Mongoose AC cord are $4999; the top-of-the-line HZ (for “High-Zoot”) cord bumps the price to $5999. The Mongoose is made by Cardas to RSA’s spec; the HZ is designed and built by RSA. The conditioners are sold by forty-five U.S. retailers and on four continents. The company plans to introduce a line of interconnects and loudspeaker cable at the Rocky Mountain Audio Fest this October.

The Dmitri is an extremely solid product; lifting it feels like lifting a solid block of metal (it weighs 67 pounds). In fact, the chassis is non-ferrous, and the front panel is pure carbon-fiber. Additional carbon-fiber inside the unit damps vibration. The unit has no switches, lights, or adjustments (except a rear-panel circuit breaker).


Over the past fifteen years AC conditioners have gone from marginal accessories to essential components of an audio system. During that time we’ve seen a wide range of designs and capabilities. As much as AC conditioning has improved the sound of audio systems on an overall basis, most of them exact some sonic tradeoffs. The typical conditioner renders a blacker background, increased transparency, cleaner timbres, and greater dimensionality, but often at the expense of compressed dynamics. The sound becomes more polite and refined, but less viscerally and emotionally involving. The better conditioners provide the traditional benefits of AC conditioning without the dynamic constriction.

The Dmitri is unique in my experience in that it not only doesn’t compress dynamics, but actually expands them. I heard this with the Dmitri powering just my front-end components, with the power amplifiers plugged into the wall outlets. (The equipment racks are at the back of the room connected to power amplifiers at the front of the room next to the loudspeakers, making it impossible to hear the entire system powered from the Dmitri.) Nonetheless, the Dmitri noticeably expanded dynamic scale and increased the sense of bottom-end heft and impact. Kick drum had more weight, body, and slam, and orchestral climaxes were more powerful. In addition to these sonically identifiable changes, music just seemed to have greater rhythmic coherence and flow with the Dmitri.

Despite the increased heft in the bottom end, the presentation was faster and “lighter.” By lighter, I don’t mean less midbass warmth or weight, but rather greater emphasis on the midrange and upper-midrange, along with greater transient agility. A car analogy comes to mind; powering my system’s front end from the Dmitri was like shaving a few hundred pounds off a sports car driven spiritedly on a twisting mountain road. The system started and stopped faster which made the music sound more lively and energetic.

The impression that the Dmitri made the system sound “lighter” extended to a significant increase in soundstage transparency, dimensionality, and clarity. I was reminded of Jonathan Valin’s evocative description of the soundstage being “illuminated from within” in reference to Audio Research electronics. This was the effect the Dimiti had—a bigger and more open quality that did indeed remind me of that special quality of Audio Research electronics. Instrumental textures were more vivid and detailed, sounding simultaneously more palpable yet slightly farther back in the soundstage. The sound was cleaner, more transparent, and paradoxically, more vivid and relaxed. These impressions were consistent with two completely different front ends: the Spectral DMC-30SS preamp/SDR-4000 Pro CD player combination, and the Pass Labs XP20 preamp/Berkeley Alpha DAC pair.

Another salient characteristic was a smoother and more gentle treble; the Dmitri took off some edge in the top end, making the presentation more refined. The reduction in glare and concomitant softening of top-octave timbres made the presentation more realistic. The tambourine in Rimsky-Korsakov’s “Dance of the Tumblers” from Exotic Dances on Reference Recordings HRx, for example, sounded a bit like chunks of metal clanging together without the Dmitri. With the Dmitri in the system, I could hear the tambourine’s individual zils vibrating with a delicacy that was astounding. By reducing treble glare and hardness, the Dmitri allowed more of the instrument’s fine inner detail to emerge. Similarly, the Dmitri made strings more silken in texture, but not overly so. This improvement in the treble would alone be worth the price of admission.

Moving the Dmitri to the power amplifiers produced an even greater increase in dynamic contrasts, particularly transient bass impacts. In fact, I’d have to say that the difference was startling. Again, this was true with two very different amplifier designs, the Spectral DMA-360 and the Pass Labs XA100.5. The midbass was tighter and better defined, and the extreme bottom-end had much greater depth and authority. Adding the Dmitri was like removing a ceiling that had previously set a limit on the system’s dynamic contrasts. With the Dmitri powering the amplifiers, I also heard the same improvements in dimensionality, transparency, and timbre I heard when the unit was feeding the front-end components, particularly the increased treble smoothness. I was left to imagine what the entire system powered from the Dmitri would sound like, but I suspect that the unit’s positive effects would be cumulative.


The Running Springs Audio Dmitri delivers world-class sonic improvements in the areas in which AC power conditioners have traditionally excelled—smoother textures, greater dimensionality, and increased transparency. But the Dmitri takes this performance to another level with a wholesale increase in dynamics, bottom-end weight and impact, and overall transient quickness. Adding the Dmitri to my system took what was a great sound and made it even better in every respect.

At $5999 with the optional but worthwhile HZ AC cord, the Dmitri is priced at the upper end of the power-conditioning spectrum. But considering the significant sonic improvements it rendered, I would consider it money well spent. This is one AC conditioner that doesn’t ask you to make any sonic tradeoffs. After living with the Dmitri in my system and then taking it out, it was immediately apparent that the Dmitri was an essential component—and my new reference in AC conditioners.


Running Springs Audio Dmitri AC Conditioner

Power rating: 2400W
Number of outlets: 10
Dimensions: 14.75" x 6" x 10.75"
Weight: 67 lbs.
Price: $4499 (with standard AC cord); $4999 (with RSA Mongoose AC cord); $5999 (with RSA HZ AC cord)

Running Springs Audio
1800 E. Via Burton
Anaheim, CA 92806
(714) 765-8200

Associated Components

Wilson Alexandria X-2 Series 2 loudspeakers; Basis 2800 Signature turntable with Basis Vector 4 tonearm, Dynavector XV-1S cartridge, Aesthetix Rhea phonostage; PC-based music server (built by Goodwin’s High-End), Spectral SDR-4000 Pro CD player, Classé CDP-502 CD/DVD-A player, Sony SCD-9000ES SACD player; Spectral DMC-30SS and Pass Labs XP20 preamplifier; Spectral DMA-360 and Pass Labs XA100.5 power amplifiers; MIT Oracle MA interconnects; MIT Oracle MA loudspeaker cables; Shunyata Hydra-8, Hydra-2, and V-Ray AC conditioners, Shunyata Anaconda and Python AC cables; Shunyata Dark Field cable elevators; room custom designed and built, acoustic design and computer modeling by Norm Varney of AV Room Service, acoustic treatment and installation by Acoustic Room Systems (now part of CinemaTech) 

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