I would completely disagree with the notion a POWER cable makes a difference.
I completely disregard that power cables, or cables that carry digital signals can make any difference.
I also completely disregard that varying qualities of copper cables, or varying 'platings' on copper cables can make a difference.
It does not surprise me that when dealing with power cables, USB cables, varying degrees of copper cables, the difference is negligable.
I am on the edge that simply changing an interconnect to solid core silver would make a difference. I would say I've heard a difference myself from just different interconnects but not in all systems. Only systems that are powered by a DAC that could be described as 'harshly detailed', do I think just an interconnect could make a difference.
However the test I would expect someone to notice a difference fairly readily is a test where someone had a 'highly detailed' DAC at atleast the expected quality of $200, something comparable to the AKG k701's and a TUBE amp that could properly power them. Then they had all $20 copper cables, and then had solid core 99.9 silver interconnects and head phone cable they could switch to. If they could not tell the difference between $20 copper interconnect and headphone cable, vs solid core silver interconnect and headphone cable in that system, I would be very very surprised.
Does a test exist that has those conditions? Or atleast somewhat close to those conditions? I have not seen them published.
I have done them on my own and have found a difference.
If you want to go around stating that you "know" something as truth, then you need to take it upon yourself to do a thorough enough investigation to state such a thing. Because thus far what you've presented is not enough evidence to say you actually know anything with certainty. You could say based on this inadequate research, and (I assume) lack of first-hand experience, I SUSPECT this is true. But to declare it as actually true? No, you are not that far along. And pleading with other people to do research for you to satisfy your interest in the subject is silly, and lazy. No one has any obligation to keep a camcorder and 'third party witnesses' on standby for everything they do in order to prove everything they say to you.
Buy yourself an adequate system, then get copper interconnects and a copper headphone cable, then get solid core silver interconnects and solid core silver headphone cable. Spend some time with them, then get someone to come in and do a blind test for you. Actually get maybe 5-10 people to do a blind test on the same system just in case you don't notice a difference. Record it on videotape if you want. Release if you want. But until then stop pretending you have an opinion more substantial than it really is.
And until then I am going to go along relying on what first hand experience I've had with this subject. However don't get me wrong here, if I piece together a system in which I cannot tell any difference between switching to all solid core silver in a blind test, I would be the first to admit it myself, and not be buying solid core silver any more.