I'll agree that, cord manufacturer claims and propaganda aside, there are some reasons to strongly suspect that exactly *why* different power cords can sound so different from one another remains fundamentally something of a mystery. I can think of a few:
> Different cords of ostensibly similar construction, all seeming to have the technical basics covered in terms of guage, shielding, materials quality, geometry, etc. -- in other words, that address every conventional explanation for why power cord construction should matter at all -- nevertheless can and do sound notably different from each other
> Different cords from the same manufacturer, supposedly differing only in their implmentation, intended useage and price but not overall design concept, nevertheless will frequently display quite different sounds, rather than one unified 'house' sound
> Even though a power cord can and will exhibit some elemental consistency of sound across different components with which it's used, power cord sound can also seem to be somewhat chameleonic, with one cord sometimes capable of sounding one way on a certain component but rather different on another
> Power cords are unlike signal cords, in that changing one can seem to change the entire gestalt of a component's sound, beyond just affecting certain aspects of it to degrees
> While most aftermarket power cords will improve on stock cords in most respects such as dynamics, articulation, dimensionality, transparency, etc., it's still not uncommon to find that overall tonal balance can be worse in some areas, or least not improved, suggesting that because a component was likely originally 'voiced' with its stock cord during the design process, any change from that cord may result in an altered balance that's not necessarily better or more accurate across the board
> Swapping between decent quality power cords will often seem to improve certain qualities while concurrently making others subjectively worse (also depending on the program material played), suggesting that it might be elusive to try and pin down concrete reasons for overall objective superiority, even though ultimately some cords are no doubt better than others, just as most aftermarket cords are better than stock ones in most respects
Personally, what it *sounds* like to me, impressionistically speaking -- this is in no way an attempt at a true technical explanation, which I'm not qualified to offer -- is that power cords somehow combine with a component's power supply and the AC line characteristics to form what I dub a "resonant signature". Anyway, that's a mental construct I use to help make sense of what I hear. In my mind, this resonant signature is unpredictable, and not well understood or engineered-in but fairly random when it comes to actual application and effects. I know that an amouphous, atechnical concept such as this won't impress the electrical engineers among us, but the fact remains that their way of explaining power cords doesn't seem to entirely square up with perceived reality for those who listen -- even those of us who (like me) have a deeply inbred skepticism (frequently outright cynicism) for almost all other forms of audio voodoo where no solid technical explanation would seem to be conceivable, and who routinely fault audiophiles for not taking psychology and methodology sufficiently into account. In short, I do think it's a fact that different power cords really do sound different from one another, but doubt that anybody has yet developed a truly comprehensive practical theory as to why in every respect.
