"So are you saysing that frequency bandwidth, and the LRC characteristics do not impact the performance of powercords the same as speaker cables and interconnects?"
No, (actually sort of yes due to reduced effect of L and parasitic C at 50 or 60 hz vs up to 20,000 hz, but lets say no for discussions sake).
What I would say is that minute differences in incoming ac, such as you might get from a new power cord are orders of magnitude lower than the constant and unavoidable ac line fluctuations that your stereo has to deal with.
Whenever someone in the house is using a hair dryer or the refrigerator motor is running or the lights are left on downstairs, or the music you are listening to changes in volume or etc. etc. ad infinitum, the incoming ac is measurably effected.
Luckily for us good designers install ac line filter networks in audio gear (and other good designers make supplemental stand alone filters for those of us are fussy). With well designed equipment the filter will do its job and protect you from being bothered by the big stuff let alone the minute stuff.
If you're oscilloscope is not giving you the resolution you paid for or if your stereo is not making your ears light up, the answer might be a relatively inexpensive line conditioner or having your existing components checked for blown caps & etc. If you can hear minute differences in ac noise due to different power cord capacitance (for example), something is significantly amiss. If you can hear minute differences in power cords but are not constantly bothered by the large scale ac line fluctuations, I think the most likely explanation is not electrical in nature.
Interconnects & speaker cables - here the designers job is to accurately transmit the most minute details of the incoming signal, and they are pretty good at it. Filtering is a 4 letter word in these applications
Happy Listening,
holdout from a bygone era :)
