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My working definition of a ground loop was equipment having multiple paths to ground combined with the fact that the earth ground might be at a slightly different voltage potential than the equipments' safety grounds. Equi=Tech defines it somewhat more simply as hum caused by the unwanted currents and voltage potentials in our electrical grounding system. In a fully implemented balanced power system Equi=Tech's directive is to "ground everything, lift nothing and connect all shields at both ends". As more equipment is grounded, the overall system in theory becomes quieter because in a balanced context all grounds are referenced to the center tap of the transformer. This is the equivalent of the zero crossing point of the AC sine wave. With no voltage or current there can't be hum. Additionally this center tap is earth grounded to drain any residual EMI and RF away from the equipment. Taking the analogy further, compare the standard RCA interconnect with balanced cables. The concept is virtually identical to that of standard AC and balanced AC. A typical RCA audio cable is analogous to standard 120V house current [figure 7] .
A typical balanced interconnection offers the same symmetry with the same inherent noise cancelling effects as balanced AC power [figure 8]. On balanced audio lines the shields are at times lifted at one end to reduce hum and ground loop noise. The problem is that while it may reduce hum the shields act as radio antennae and pick up RFI from the environment. This can be a serious problem with computers, MIDI gear and other digital systems. Consider the time and effort we take to integrate and match our equipment for ultimate system synergy yet we don’t perceive electric power as an integral part of this system. Equi=Tech views electricity flowing into the system and the audio signal as two aspects of an integrated whole.

The digital domain
Although I am a committed vinylphile, balanced power offers solutions for the digital side as well. While hum is often the noise indicator for analogue sources, it’s a little different for digital with the inherent noise from its power supplies, HF pulses and jitter. Jitter is distortion caused by timing and deviation issues in the high-frequency digital signal stream. Martin adds that "digital jitter is caused in part by high-frequency electrical interference approximating the bit stream rate of the digital signal." Specifically he compares digital jitter to intermodulation distortion in the analog realm where each piece of digital equipment cumulatively adds to the jitter problem.

The claimed improvement from balanced power is startling. Martin claims that the Equi=Tech system reduces average jitter by up to 50% and peak jitter by up to 66%, with the only variable being the change from standard to balanced power. The high-frequency noise reduction claims are equally as dramatic. "... nulling low-frequency harmonic current in essence 'knocks the legs out from under' the high-frequency harmonics in the AC system. Everything collapses." Bold claims to be sure and I have no way to prove or disprove them but Martin cites tests in both audio and technical environments. Oak Ridge National Laboratory was having significant problems with an electron microscope blurring the images of silicon atoms. The cause was tracked to minor timing errors in their digital data stream. The change to balanced power reduced jitter and cleared up the images. So much for theory. Now let’s see if the sonic improvement lives up to its promise.

Although my 10WQ is permanently installed I could easily A/B the system. My dedicated room was built with two independent power systems - balanced power to all equipment and a parallel set of outlets with standard 120V. The Romex runs are the same length using the same wire. The only difference is that the balanced system uses a higher grade Oyaide outlet.  In less than five minutes I can convert the entire system from balanced to unbalanced power. I expected this to be a fascinating test as my electronics—including the Walker phono, VTL 7.5 preamp and Tenor amps—all have superior power supplies. Add to that the excellent Silent Source power cables and I was hoping for an interesting showdown between regular and balanced power. Since this is a comparative review I wanted to be careful about the bias many reviewers suffer. In any comparison you take a series of small differences, stack them up and sometimes present an overblown conclusion.  One of the purposes of a review is to clearly differentiate between choices. It would get pretty boring and meaningless to report that it all sounds the same. Hence I believe we sometimes exaggerate differences. 

Having used Furman balanced power in the past I anticipated subtle improvements whilst being aware of my expectations. Even so preconceived notions were quickly blown away. While I expected refinement I heard something more substantial. The differences were significant and immediately audible, on par with the upgrade of a new piece of equipment but not limited to one specific area. The balanced power effect touched almost every area of the sonic spectrum. Let’s start with something unexpected. My initial impression under balanced power was an increase in loudness. At first I thought it to be a music-specific phenomenon but the effect was consistent from Beethoven to the Beatles. It took me a while to understand this. The VTL preamp has a digital display so the system levels were unchanged. I broke out my NTI SPL meter and could detect no variations. If the music was not physically louder, why the strong initial perception? This took some additional listening sessions to unravel. I have at least a working theory now and it pertains to the global reduction in noise.

I first wanted to get a base line on the inherent audible noise with and without balanced power. The VTL is a top performer in many ways but with its tube and circuit design not dead quiet. Put your ear a few inches from the tweeter and you get the faint rush of tube noise. Measuring with the NTI meter at 8 inches on axis from the tweeter without signal the noise level under balanced power was .3dB to .8dB lower than with standard unbalanced power. Under regular power there also was a faint but audible 60Hz hum. While real and measurable this by itself did not account for the loudness perception. If we go back to theory, ground noise and other grunge not only produce audible noise but intermingle and essentially destroy or mask low-level detail. The micro details are lost in the inherent system noise and dynamic range and contrasts are reduced. Imagine music played though a car radio with limited dynamic range and road noise. Musical peaks are barely recognizable. Now shift to your balanced system with its new ultra quiet expanded range. The crescendo explodes from nothingness to startling realism. The result is perceived loudness but in reality you are hearing greater dynamic range. The quiet has become quieter. This increases the peaks' tallness.

But this went farther than just the contrasts between loud and quiet. The 10WQ changed the dynamic gradients. The incremental dynamic contrasts with standard power seemed chunky or coarse by comparison to the smooth scaling with balanced power. Instead of stepping, music naturally flowed from one level to the next. In every instance— especially those with complex orchestrations—there was significantly more air and space around instruments and voices. There is cleanliness and precision where standard power is somewhat opaque and congested.

With my system it was instructive to not just describe the effect of balanced power but also the effect of removing it again. Each time I did the soundstage shrunk in all directions. My internal visualization of a soundstage is analogous to a three-dimensional sphere. While listening with standard power, my listening notes were peppered with points describing a smaller contracted musical sphere. Music appeared to originate more from physical constraints between the speakers, with far less depth. It ties to another consistent observation of a more forward sound with the Equi=Tech. With standard power I was much more cognizant of the sound emanating from the speakers. With balanced power I was far more immersed in the sound field. 

When it came to bass I had expectations again. I believed that the Equi=Tech would produce more prodigious bass. Wrong. There wasn't more amplitude even on the plummeting opening of Morph the Cat. What you do get is definition – powerful tight and controlled blooming into the room. Standard power sounded boomy, loose and flabby. This might not be that objectionable until you hear it corrected. Now bass has far clearer focus and resolution. That's how it should sound!

Flipping back to standard power the system sounded slightly hard, rough and ever so slightly unrefined. The sound had less drama and emotion. The performance with the 10WQ was smoother, more at ease, polished and sophisticated. Balanced power presents a more refined sound that flows and emotionally draws you in. It's more at ease and more organic. There is smoothness but not in a negative way. There is no rounding or blunting of the leading edge, no dullness. Voices are far more relaxed and renewed with natural purity. Under balanced power I never bumped up to a volume limit as that definable moment where the sound turns strident. With regular power I found myself at times unconsciously reaching for the remote to turn the volume down. Maybe this was due to inherent noise or a form of IM distortion but regular power sounded brighter, harder and a little more brittle. The Equi=Tech system scaled with seemingly endless power reserves and the timbre or tonal color of the music stayed consistent with virtually any volume setting.

When describing power conditioning among reviewers it appears mandatory to describe the blackness of the noise floor. While I have used the term myself I believe there to be a better analogy. Blackness is a static concept yet music is dynamic and flowing. What we are really saying is that with a lower noise floor you have a greater sense of the smallest micro details emerging from the depths. Yes color can describe the background but for me it is more about musical flow of detail.  While the background is blacker with balanced power, more importantly the silence allows the emergence of a far more nuanced presentation to pull you in. Chicken or egg - does the enhanced detail of balanced power give the appearance of quieter backgrounds; or do quieter backgrounds allow for more detail to emerge?  Does it matter?  Either way the 10WQ offers some pretty big improvements.