I have neither "golden ears" nor deep pockets, but I can hear the difference upgraded power cables make in many systems. To those who say it is only a placebo effect or the results of expectation bias, I challenge them to just try some aftermarket cables and listen.
Like some of the previous posters, in my experience the differences in power cables are more revealing after long sessions of listening to familiar music. A/B testing, for me at least, does not tell me much (as I suspect the influence of expectation bias nulls any critical analysis). I find that general satisfaction, pleasure, and involvement in the music are the more telling aspects of whether an upgraded power cable makes any difference in any given system.
Most manufacturers of quality audio components will include an adequately specified power cable for average conditions with their equipment. Your individual system may or may not benefit from a different cable. I agree with the arguments some of the previous posters made regarding the economics of including anything more than an adequately specified cable with their components. It is fun and interesting to try different things out with your system under your conditions. Just like tube rolling, trying out different inter-connects and speaker cables, room treatments, DSP, etc., upgrading power cables can sometimes produce profound changes in your listening experience.
