How can power cords make a difference?

Dear All,
I've certainly read a number of interesting theories on why PCs make a difference. RF/EMI rejection, bigger guage "pipe" to supply electrical power, bandpass filter effects, various sound differences between metal types and purity, mechnical vibrational effects, soldering techniques, noise cancellation techniques and the dielectric content to name a few. Here's a thought. I've read about but never experienced the PS Audio PowerPlants. I've read that changing the output frequency can effect the sound. Sometimes better, sometimes worse. Perhaps the PC is merely removing certain frequencies from the incoming power or modifying the wavelength (or waveform) slightly.
I know that adding Uninteruptable Power Supplies (UPS) to complex laboratory medical equipment makes them run better. Repair costs go down, system failures go down, mechanical irregularities go away and precision improves. D/A and A/D convertors certainly work more consistently. There are power supplies inside the equipment that should protect and clean up the power. I've noted times when the power monitors showed no spikes or brown-outs but the UPS aided equipment ran better. So what's up? Personally, I don't know (I was a chemist not an EE). I can usually hear differences between PCs. Sometimes I like them, sometimes I don't. Hey, enjoy the music. It's not worth fighting over.

this is good:
http://www.audioasylum.com/audio/cables/messages/13538.html

I'm going to take a whack at this and would first like to establish my credentials. My experience with the scientific aspect of electronics is limited to the DYNA ST-40 amp I built back in the 70's. When I was done and put the cover on the box, I was struck by the little yellow label that said, "caution, no user serviceable parts inside". Truer for me than, I suspect, for many kit builders.
However, I do know a few things about science and the philosophy of science. One of those is that there is something called "electron theory". No one, not any of us or any Nobel Laureate KNOWS what electrons do or if they even exist as the theory supposes. It is just that, a theory.
I regard audio equipment designers, for that reason, as wizards in the true sense. They manipulate forces beyond their understanding to perform miraculous feats. Stevemj and 70242, on the other hand, are like the 14th generation of high priests who keep the scrolls that they can't read but you'd better not look directly into the eyes of the idol or you'll be struck down.
Way back when, kids rolled paper into a cone, stuck a needle through the narrow end and held the needle to one of dad's 78's while it rotated on the Webcor. Sound ensued. How much difference is there between that and a Goldmund Reference? Only one of degree. One has a suspension based on theory, the cone doesn't. One has amplification of the vibrations based on theory, the cone doesn't. The child with the cone doesn't know why there is sound, but empirically, there is. The modern turntable designer likewise doesn't know, although he'll probably tell you he does. His work is the result of empirical observation and a "belief system" grounded in a theory, not in fact. We laugh at the notion of an 18th century Dutch scientist who believed a little person he called a "homonculous" bent the light through a prism. Everyone knows that Newton "proved" that the light was bent due to the refractive nature of the glass' shape. Yet, we don't know why that particular shape bends the light, only that it does.
Electromagnetic theory "supposes" invisible, "sub-atomic" particles that have cause and effect. We can only observe the gross consequences of the theory. Where a finer understanding is desired, such as what is going on inside a power cord or a transformer, with impossibly tiny amounts of a theoretical concept called "current", we rely once again on empiricism, not objective truth.
Ohm's Law is not a law. It is a mathematical formula that allows "theorists" to predict the behavior of current, which, once again, is part of a theoretical model. Heisenberg's "Uncertainty Principle", while elegant and brilliant, is more of an apology for the inability to observe energy than an attempt to explain it.
When the so-called "objectivists" deride the notion of our tweaks, condescending to admit that perhaps any audible differences stem from something "outside of the LAWS of science, as we know them", that is the worst sort of hypocrisy and a telltale that they have no understanding of the true Science that lies at the foundation of rational thought.They are simply acolytes who guard a temple of their own creation to defend themselves against forces they do not understand.

Stevemj. I am not opposed to ideas, only to comments that scientific evidence is necessary to prove that something works. I am very confident of my hearing and the results of my testing. I think that if those of you that disagree that power cords make a difference could hear a test on my system, you would understand. The differences are so dramatic, that even within a large group of listeners, there is no doubt as to the change.

I never claim that only one (certain) power cord or interconnect is the perfect answer. In fact, differences in power cords are sometime inconsistent between one piece of equipment and another. I have no explanation for this, I only know it that is audible, repeatable and difficult to explain. My wish is that those of you that are driven toward the scientific method could find instruments that measure what many of us are hearing. Both sides would have a better understanding and perhaps these methods could assist with design that current technology cannot address.

I don't expect to ever solve all the problems of reproduction of music as it is far too complex. However, the person who asserts that a particular product cannot possibly make a difference, has no chance of solving these problems, because they close their mind to the opportunity of learning something new.

My rejection of ABX or double blind testing, is not because I dismiss this testing procedure for all things, but rather because it is not applicable to a complicated music system. Power cables in my system (as a specific example) radically change sound simply by picking up a cable and letting it drop to the floor. The same disturbance occurs when I gently pick up my amp to change an isolation device under it.

No other mechanical or electrical change is required, the amp may simply be picked up and set back down with the same disruption of sound. The return to the original sound requires from five to fifteen minutes. Such strange behavior from wire is why I consider it impossible to do ABX testing. Humans cannot ignore this initial change (moving the equip) and confuse that first impression with (being) the final result. Worse, by switching multiple times in a single evening, to equalize the ABX test, the cable is disrupted so often, it is never totally correct.

I wish you and 702 lived close enough to do a relaxed listening session with me. It would be a slow process, because I am likewise convinced that we are all affected by the presence (and attitude) of a new visitor/listener as well. In the end, I am certain there would be little to disagree about, provided we stayed the course with the music and the possibility of learning.

Kitch29 -

Your lack of knowledge of science, electronics, audio, the definition of a theory, EVERYTHING that you mention in your diatribe is so staggering as to be beyond comprehension. The number and magnitude of fundamental errors in your post is truly frightening.

You'd be wise to take a beginning science or engineering course, and get at least a modicum of understanding (rather than just pretending to) before spewing forth as you just did. It's really quite embarrassing.

Sadly,
Jhunter