I'll qualify my post, as I am a former consumer, reviewer and now marketing and sales person for a company that manufacturers, among other things, power cords.
From within the audio/video trade industry and in professional audio, the "power cords are snake oil" issue is entirely moot. For any that have experiemented, ALL that I know, have purchased and continue to use and endorse some type of specialty power cords, whether in film studios, mastering labs, recording studios, trade-show or electronics design systems.
These professionals didn't purchase aftermarket power cords on a whim or because of a "buzz" or a media review. They purchased them after thorough testing within controlled environments, and within electronics systems that are among the most highly calibrated systems in the world.
Of course, consumers will have varying experiences because of the wide range of systems and contexts power cords are applied in. Forget power cords for a moment, as there are still some that believe most SS amps sound the same and that CD replay stops improving at the $1000 price point. These threads also pop up on the talk boards from time to time and they are equally, er, profound. There are different points of experience across the spectrum, and arguing individual experiences on-line is an extremely complex and non-productive pursuit-- imo.
Because power cords are largely available for personal testing with no cash outlay for anyone that wants to listen for themselves, that would seem the logical course for the curious. On-line argument is for those who will hold their untested beliefs and theory above all evidence and explanation, measurements, graphs etc. For them, the argument IS the point and the hobby, not what may or may not be true. If truth were the target, then these raging debates would be a lot more collegial and less polarized or pointed.
The technical reasons power cords can improve the sound or visual displays from systems of electronics have been explicated here and on AA countless times. 5 minutes spent serching will illuminate many legitimate reasons why power cords or conditioners have the capability to affect sound. I include conditioners because they often incorporate similar design impetus and material constituents as power cords. The big difference in many cases is that they are a "box" and specialty power cords are not. Capacitors and inductors can be put into power cords, and there are some companies that use these. Obviously, these products now have reactive elements in them that at the very least will have a strong and empirically well grounded "chance" to effect a noticeable change in the performance of the applied device.
The most obvious element in this non-issue is that by far the vast majority of consumers who have tried a decent variety of power cords know that some make a noticeable, repeatable difference in performance. For example, they know that a power cord using silver, or ribbon conductors will often "sound" very different from one that uses solid core or stranded copper.
The VAST majority of those that rail against the possibility of a power cord effecting a positive difference are those with NO experiential evidence to back up the claims they make. Jetmek above is the first person I've seen who rattled off some names of power cords and claimed to hear no difference, although there wasn't any specific context offered to butress his stated experience.
In this industry, I know from personal experience that the priciples of many electronics and speaker companies have experimented with a variety of power cords--extensively, and have chosen to use them in their reference, development and trade show systems. Why would any electronics company want anyone to think that their electronics could be improved by a power cord? Because they no them to work. These are all companies who arguably, make some of the most recognized and better designed electronics in our industry.
Audio Research
Balanced Audio Technology
Halcro
Classe'
Jeff Rowland Design
Pass Labs
ART Audio
SIM Audio
Edge Electronics
Musical Fidelity(US)
Wilson Audio
Verity
There are many, many others, but this short list will suffice to make the point.
What about pro-audio? The empiricists? Mastering engineers? Recording engineers, Record producers, recording studios, film studios? What motivates these people are results.
All of the following well know pro's and studios have chosen to use aftermarket power cords in their systems after extensive testing revealed obvious performance improvements, and repeatable results.
Sont Music (Mastering systems--Japan)
Philips (US Crest National Film studio and SACD production plant)
Memory Tech ($100 mil. Japanese CD/SACD corp)
Astoria Studio (Dave Gilmour's studio UK)
Doug Sax (Mastering engineer)
James Guthrie (Mastering engineer)
Rick Rubin (Record producer)
There are many more, but these electronics manufacturers, studios and engineers are invested solely in the bottom-line of achieving enhanced performance. They develop their testing and recording systems with products that let them hear/see what is going on within the recording, or the electronics/speaker design.
Aftermarket power cords will not work in all systems or for all people as contexts and individual differences vary so widely. That is why most companies and dealers offer trials so each person can determine the efficacy and value of a a specific PC design for themselves.
I see two hobbies evlolving on-line. One is the enthusiast high-end hobby where shared experience is the point of the thread. The other is the endless debate and argument hobby. I suggest leaving argument to the "pro's", and finding ones own experience to share with others.
Best,
Grant