Is it all in my head??

I am so old that I remember the time when the AC power cord was used as the antenna for many receivers.

Shielding, wire geometry, wire quality, and wire gauge will all affect the sound quality of the power cord. That being said, an expensive power cord won’t polish a turd, so you have to be aware of that limitation.

Some power cords will really make a component sing and you will be shaking your head in bewilderment.

ozzy

Nonoise and ozzy both just hit the nail in the coffin! 

@nonoise,

"Your hearing is completely different from someone else.
You’ll have some overlap but your hearing is unique.
Your amp won’t have the same output specs as others.
Your speaker won’t have the same input specs as others."

Not sure I get that part... That's what the skeptics say to us about fuses, wiring and everything else controversial...that we lack either the educated ear or the technical skill to interpret the results of our own observations, and that therefore we shouldn't even attempt to find out on our own what might be going on. But, for the life of me, I don't get why we wouldn't do so, if we have an opportunity in front of us. Why would audiophiles trust their ears with speakers, with amps and sources...but Not with wiring? Makes no sense to me... I for one am not looking solve the 'mystery of all wiring', just to see if I can unearth the kind of things the makers are not telling me. Your post above makes it look like all investigation on the topic should be banned or dropped. Oh sure, some folks might be in need of starting over from the beginning when it comes to dreaming up an experiment that is dirt simple enough to be factually useful, yeah, I'll grant you that might be a fair criticism, but I mean should we deny other peoples right to experiment...or just maybe be willing to call into question the results on occasion. Just sayin', is all.

Regards

Far more likely that you are hearing a difference than it all being a figment of your imagination. 

waltertexas

If you like the Kimber cable sound and improvement then 
maybe you should stay with using Kimber cables and move up to a higher grade that they make .
Synergy can be an elusive find , so changing cable manufactures could prove positive or negative sonic effects .

nonoise makes a good point , you've started now go from there .