When a power cord could obviously affect SQ

as many people have said the recommended upgrade from the manufacturer is a great place to start
 

The reason that 6 feet of power cord matters is because we're dealing with alternating current that vibrates not direct current that flows 

if it was a direct current issue coming from 100 miles away, it would be a different world, but with alternating current, we're talking about a vibrational AC wave in the room and that 6 feet of power cord is an antenna

for noise above human hearing

why do we care about noise above human hearing? Because it affects the shape of the AC wave

and that affects the power supply

and that IS audible.

the better your system the more obvious it will be, but as a user of Shunyata research power cords, those are obvious in any system

@retiredaudioguy 

How is the cable rolling going?

@mclinnguy I have tried my MIT Z-Cords and the TriodLab cables.  I don't think I hear any difference.

@tuberist wrote:

Many here will say power cords will have a sonic impact if you have a resolving system.

Yes, you might think that a resolving system is key in discerning the kind of minute sound quality differences a power cord might make.

Not so, apparently:

@jbuddha882 wrote:

Came home and [...] all I had was a pair of KEF Q3 meta bookshelves and my AV receiver for the home theater, Onkyo TX-NR7100 integrated amp. The first thing I noticed, within 10 seconds of play time at LOW TO MEDIUM volume, was just plain more MEAT on the bones [...] the sound mainly got “thicker”, meat on the bones is what I can honestly say. Worth the $400 bucks, entirely. 

It's good to know that you don't need a good system, you just need good cables.