I have a friend that owns a local wire plant. As a result I can get just about any cable configuration made up for me (as long as I don't do it too often). But I enlisted him in an experiment to find an ideal power cable. We tried a lot of things and found that if we changed anything about the design or materials, we could hear the effect. I must admit the quest was very confusing and perhaps a better knowledge of the scientific issues may have helped us. It took a long time before we understood how to make a good power cable. At the end of it I had a lot more respect for audio cable companies, and a lot less tolerance for those that complain about the difference between the retail price of an audio cable and the apparent worth of the ingredients. The costs must be significant in design and experimentation, not to mention marketing in a very crowded market. But I guess my real point is I could hear the difference between cords that had only subtle differences in their design, so I find it very difficult to understand how others cannot. On the other hand I put a lot of time into helping others set up their systems and I have got to say some audiophiles live with some terrible sounding systems through lack of knowing about setup and room treatment - in such systems I can imagine why cables do not sound different.
