Audphile1 - No issues here. I suspect, but don't know, that the reason power cords are not a worthwhile investment to me is your item #2. Most of my equipment has pretty robust filtering, by the time the ac gets all the way to the dc buss it has seen two or three filter networks. If I had equipment designed with sort of the minimalist/purist approach it might well be more sensitive to ac input variance. The other thing that might be hiding power cord effect is that I've got components plugged into line filters, so any gain you get from a cord acting as a bit of a filter network to keep component 1 from creating ac hash for component 2 is probably dealt with in the filter. All that being said, I really do believe that a lot of people would save a lot of money if they would test things in at least a quasi scientific fashion to eliminate hearing what they think they should. Often when you notice that "a veil is lifted and I can hear things I've never heard before" , or some such, it is because you are concentrating more when listening to the new gadget.
Happy Listening!
Happy Listening!