Many years ago, shortly after taking an interest in high-end audio, I learned an unassailable audio truth: never, ever doubt the performance benefits of good AC power. But even after many years, whenever I upgrade my power cords, line conditioners, AC outlets, or fuses, I continue to be amazed at the reduction in noise and the improvements in detail, transient speed, dynamic range, imaging, and three-dimensionality. It’s a lesson I learn over and over.
I frequently receive new power products for review, and am pretty good at keeping up with industry news. Yet it seems that every few weeks I discover another maker of power products I’d never heard of. Reading the company’s website or new-product announcement, my eyes usually glaze over, and far more often than not, I never hear about that company again.
But when my editor mentioned Essential Sound Products, my interest was piqued. First, it’s been almost 20 years since ESP’s Essence power cords and distribution strip made a huge splash. Back then, the fact that a high-quality power cord could improve a component’s sound was not as generally accepted as it is today. ESP was one of the first companies to prove otherwise.
Second, over time, ESP’s products have become popular with professional audio engineers. In fact, the company’s products have been used to make, mix, and/or master recordings by Gerald Veasley, Keith Jarrett, and others.
With this type of history, I was curious to hear what ESP is up to now, and agreed to review their Essence Reference-II power cords and power distributor, both of which are now in their fifth generation. Shortly thereafter, Michael Griffin, the company’s founder and president, sent me enough product to outfit my entire rig: two 3m-long ($2199.99 each) and three 2m-long ($1999.99 each) Essence Reference-II cords, and one Reference-II power distributor with a slaved 2m Essence Reference-II cord ($2999.99 each). Total price: $13,399.94 USD.
The Essence Reference-II power cord uses a patented multi-conductor approach in what ESP calls an Essential Lay. Each cord contains four 20AWG copper conductors spaced so that there is no room for air gaps or soft filler materials. Per ESP, this geometry results in the cord maintaining its physical integrity and sound even when bent.
The conductors are covered by an inner PVC jacket. This in turn is covered by a braided copper shield, to prevent radio-frequency interference (RFI) from being picked up by the cord and electromagnetic interference (EMI) from leaching out, which would cause signal distortions in nearby speaker cables and interconnects. The shield is wrapped in another jacket of PVC, and that jacket is covered by an outer sleeve of woven polyester.
The cords are terminated with Furutech connectors whose terminal blades and pins are made of high-purity, unplated copper. After the connectors are terminated, ESP fills them with epoxy. According to Griffin, the epoxy and PVC insulation that surrounds the conductors have similar dielectric properties, and the resulting continuity in the dielectric path eliminates a potential cause of phase distortion. He also said that the epoxy prevents oxidation and corrosion, enhances mechanical stability, and protects from strain the fragile conductor terminations.
The conductors and connectors of the Essence Reference-II cords are cryogenically treated at temperatures as low as -300° F. According to Griffin, this irreversible process alters materials such as copper and brass at the molecular level by aligning crystalline grain boundaries to improve the current flow.
The Essence Reference-II power distributor’s size (about 19”L x 3”W) and somewhat cylindrical shape make it look like an ordinary power strip. A closer inspection reveals it to be anything but. ESP is aware that many customers place their power distributors on the floor, where they’re subject to structural and airborne resonances. Because of this, the Essence Reference-II includes several features that are aimed at damping such resonances. First, the Distributor weighs a hefty nine pounds. Second, the walls of its metallic-silver aluminum case constantly vary in thickness. Third, those walls are coated with a proprietary, anti-vibrational potting material.
The exterior of the distributor’s case is ribbed and finished in the same manner as an automobile. An electrically charged primer, which creates a tight bond to the metal, and a sealant are applied to the case’s surface, and then a clear, hard, durable overcoat is applied. The ends of the Essence Reference-II are fitted with polycarbonate caps. According to Griffin, this material is expensive, and is impact-resistant and chemically inert; it looks great.
On the top of the Essence Reference-II are eight hospital-grade (green-dot), isolated-ground receptacles custom-made by Leviton to ESP’s specifications. The positive and negative contacts of typical hospital-grade receptacles are made of plated brass comprising about two-thirds copper and one-third zinc. ESP’s contacts are unplated, made of a bronze that’s over 98% copper, and specially designed to tightly grip the prongs of male AC plugs. According to Griffin, the high copper content gives the bronze a warm, natural sound.
The isolated ground contacts of high-purity copper are made from a single stamping, are physically separate from the chassis and chassis ground, and are wired directly into the power-cord ground. This, according to Griffin, helps prevent RFI contamination and minimizes ground loops. Griffin also claimed that the use of nonmagnetic aluminum for the case provides excellent shielding.
The Essence Reference-II’s internal wiring is coated with the aforementioned anti-vibrational potting material, and the same 20AWG conductors used in the Reference-II cord are used to wire the positive, negative, and ground connections for each of the distributor’s receptacles. This wiring is laid out in a star or “home run” configuration in which each receptacle is directly and independently wired to the cord, and thus isolated from the receptacles. According to Griffin, a proprietary termination process reduces resistance in the connection between conductors and receptacles.
Unlike with a number of high-end power boxes, where you have to shell out extra bucks to separately purchase a power cord, a Reference-II cord is hardwired to the power distributor rather than attached via an IEC connection.
The distributor protects components from power spikes and surges, and its ceramic-bodied fuse provides protection for severe overload occurrences. As with the Reference power cords, the power distributor’s conductive materials (i.e., outlet assemblies and internal wiring) are cryogenically treated.
Looking over the power distributor, I couldn’t help notice that it is passive -- it contains none of the discrete capacitors, transformers, chokes, or filtering devices found in many active conditioners. I asked Griffin why ESP chose this design approach. His reply:
The Reference-II power distributor does filter. . . . You are welcome to try it with other power cords and compare its performance to other line conditioners. I tell customers that our power distributor does what you wish a line conditioner would do, only better. It improves clarity and tonal balance, dynamics and transient speed, and lowers the noise floor. Also, it affords surge suppression. What more would you ask of a line conditioner? We chose not to associate the term “line conditioner” with our power strips because many customers have preconceptions about the performance of typical line conditioners -- the negative effects some have, such as imparting a more sterile or lifeless character to the sound or introducing audible hum noise.
Unlike many high-end power cords, which are advertised as being thin and flexible, ESP’s Reference-II cords actually are -- they won’t lift your components into the air. Nor will they break the plastic IEC sockets of heavy components that refuse to move. Each cord comes packaged in an attractive zippered bag of silver nylon that ESP claims is the same material used to make astronauts’ spacesuits.
ESP provides a lifetime warranty on its power cords and distributors. Although this warranty is nontransferable, it’s head and shoulders above what’s offered by most other makers of AC power products.
ESP doesn’t make application-specific (e.g., amplification, source, digital) power cords. Rather, their cords can be inserted anywhere in your system. I began by removing my Synergistic Research line conditioners (two) and power cords. I then plugged the ESP distributor into my wall via a Synergistic Tesla Plex SE AC receptacle and an Acoustic Revive CFRP (carbon-fiber faceplate) and CB01DB receptacle base plate. I used the 2m ESP cords to power my Esoteric C-02 amplifier, A-03 preamplifier, and K-01 SACD/CD player. Finally, I connected the 3m ESP cords to the active bass modules of my YG Acoustics Kipod II Signature speakers.
Michael Griffin put several hundred hours on each of the review samples before sending them to me. After setting everything up, I let them play for another 100 hours, to give them time to settle in.
As promised, the ESP gear produced a sound that was full-bodied, rich, and warm. Even so, they didn’t unnaturally skew the tonal balance. I’m very familiar with the Lancastrian-accented voice of Jon Anderson, the former lead singer of Yes. In fact, during my misspent youth, I attended over 20 Yes concerts. More recently, I’ve seen Anderson perform in extremely small venues, in which he’s taken to telling the audience interesting and often humorous stories, sometimes without the use of a microphone.
With the ESP gear in my system, Anderson’s voice in “Flight of the Moorglade,” from his Olias of Sunhillow (CD, Atlantic 80273-2), was tonally spot-on. The added body only enhanced the realistic nature of the sound. Indeed, the ESPs’ warmth favored many of my rock CDs and digital files, which too often sound bright and overemphasized in the upper midrange and lower treble.
The ESPs produced bass and midbass that were consistently accurate, tight, and tuneful. The double bass in the opening of “Honeysuckle Rose,” from Jane Monheit’s Taking a Chance on Love (16-bit/44.1kHz FLAC, Columbia), oozed warmth and presence. The leading edges of the plucked notes were cleanly presented, and my feet tapped from the first note.
Although “A Man Needs a Maid,” from Neil Young’s classic Harvest (16/44.1 FLAC, Reprise), is a pretty decent recording for a rock classic, it’s not perfect. Aside from some analog hiss, there are several instances of low-end distortion, as when the lower strings of the London Symphony Orchestra enter -- a pair of cellos or double basses (it’s hard to tell which instrument is used, as their frequency ranges overlap). Depending on the gear used, the distortion of the string resonances is somewhere between just detectable and downright intolerable. Through the ESPs, the distortion didn’t sound overemphasized, and the recording was more listenable than through almost any other cord I’ve tried.
The ESPs also rendered crisp, lively transients and very satisfying upper-end air and extension. In “Searching for the Right Door,” from Billy Cobham’s Spectrum (24/192 AIFF, Atlantic), the splashes of hard-hit cymbals were brassy and otherwise impressive, if not quite as powerful and extended as I’ve heard with the very best -- and, typically, über expensive -- power cords.
Finally, the ESPs revealed the details that I’ve come to expect from good high-end power cords. Pianist George Winston is known for making exceptional use of the sustain pedal, which lifts the dampers off a note’s strings so that they resonate long after the key has been released. Since effective use of the pedal can enhance expressiveness, the pedal is known as “the soul of the piano.” The ESPs wonderfully revealed the mechanical sound of the sustain pedal in “Loreta and Desirée’s Bouquet, Pts. 1 and 2,” from Winston’s Summer (16/44.1 FLAC, Windham Hill). They also impressively captured the long resonances that are Winston’s trademark.
The ESP products made a great showing in my listening room, doing many things right and having no serious flaws. At over 13 large for a full-blown two-channel setup, though, they run into some very serious competitors that are made with very innovative materials and processes. For my money, Synergistic Research’s power products set the performance bar. And there are other strong contenders, such as the quantum-based products made by Bybee Technologies and Nordost.
My current two-channel power setup includes active Synergistic Research Element-series power cords and two daisy-chained Synergistic line conditioners: a Powercell 6 SE and a Powercell 10 SE Mk.III, the Powercell 6 used solely for digital components. Active biasing is provided by a Synergistic Enigma tube power supply that sucks in current through two additional power cords. Throw in a Synergistic QLS line strip or two and the total power-conditioning tab, excluding the AC wall-outlet system, far exceeds the cost of the ESPs.
To level the playing field, I unplugged most of the above and compared the ESP power cords to Synergistic’s Element Copper-Tungsten cords ($1800 per 5’ cord). However, I was at first uncertain as to whether I should compare the ESP power distributor with my passive Synergistic QLS 9 line strip ($450) or Powercell 6 SE line conditioner ($3795 with upgraded power cord). Cost considerations dictated the latter. There was also Michael Griffin’s e-mail, quoted above, in which he invited me to compare his power distributor to any line conditioner.
In light of the above, I used my Powercell 6 SE without the Powercell 10 SE Mk.III. Since the Synergistic cords and line conditioner are active, I needed AC receptacles for their wall-wart power supplies (which Synergistic calls Mini Power Couplers, or MPCs). I also required receptacles for the active bass modules of my YGA Kipod IIs and my amp, preamp and disc player. No single line conditioner or power strip would provide me with enough outlets, so I pressed back into service a Synergistic QLS line strip.
I began with Neil Young’s “A Man Needs a Maid.” The Synergistic gear more ruthlessly conveyed the distorted resonances of the orchestra’s lower strings than did the ESPs. Nonetheless, despite the ESPs’ forgiving nature, there was little dispute that the Synergistic products provided the more accurate and revealing sound. With George Winston’s Summer, the YGAs now differentiated between the initial impact of the pianist’s shoe against the metal sustain pedal and the more muffled sound of the felt-covered part of the pedal shaft inside the wooden pedal box.
In “Tamarack Pines,” from Forest (CD, Dancing Cat D106885), Winston repeatedly strikes what sound like several keys that are immediately below the instrument’s very top note. The resulting pitch is so high in frequency, so repetitive, and so closely timed, that the wooden undersides of the keys can be heard striking the key frame. With the Synergistic products in the loop, the YGA speakers more clearly and cleanly conveyed these jarring percussive attacks.
Essential Sound Products’ Essence Reference-II power cords and Reference-II power distributor won’t be here today and gone tomorrow. Rather, they’re based on proven technologies in an industry in which marketing hype and dubious technological claims are all too common. Yes, there is some tough competition in the high-end power game. However, chances are that the ESP products will substantially improve your system’s sound. Undoubtedly, they’ll make you realize, for the first time or the fifth, that you overlook the benefits of good AC power at your own risk.
. . . Howard Kneller
- Amplifier -- Esoteric A-02
- Preamplifier -- Esoteric C-03
- Sources/DAC -- Esoteric K-01 SACD/CD player; EMM Labs DAC2X DAC; Weiss MAN 301 music server; Apple MacBook Pro running Amarra; Windows 7 netbook running JRiver Media Center 17
- Speakers -- YG Acoustics Kipod II Signature
- Interconnects -- Synergistic Research Element Copper-Tungsten-Silver (components, active bass modules of YGA speakers)
- Digital cables -- Synergistic Research Tricon USB and Active FireWire 800
- Speaker cables -- Synergistic Research Element Copper-Tungsten-Silver
- Power cords -- Synergistic Research (all): Element Copper-Tungsten-Silver Analog (amplifier, preamplifier), Element Copper-Tungsten-Silver Digital (disc player, DAC), Tesla Precision AC SE (speakers), Element Copper-Tungsten (Powercell 6 SE and Powercell 10 SE Mk.III power conditioners), Element Copper-Tungsten-Silver Analog and Digital (Enigma power supply fed by two power cords), Tesla Hologram A (QLS Lines strips with Galileo MPCs)
- Power conditioners and distribution -- Synergistic Research Powercell 6 SE (digital only) daisy-chained to Powercell 10SE Mk.III
- Isolation devices -- Custom Isolation Products amp stand (source), Bright Star Audio IsoRock reference platform (preamp), Silent Running Audio VR fp Isobase (amp), Synergistic Research MIGS, Mapleshade Heavy Hats, DIY amp stands
- Misc. -- Synergistic Research (all): Galileo Universal interconnect and speaker-cable cells, Acoustic Art System
Essential Sound Products Essence Reference-II Power Cords
Price: $2199.99 USD per 3m cord; $1999.99 USD per 2m cord.
Essential Sound Products Reference-II Power Distributor
Price: $2999.99 USD.
Warranty (all): Lifetime (nontransferable).
Essential Sound Products
PO Box 81998
Rochester, MI 48308-1998
Phone: (248) 375-2655
Fax: (248) 375-2701