Worth upgrading my cables?

my electrician audiophile friend remains in amazement over the difference cables make, even after 20 years of experiencing it, as it technically makes no sense to him...fortunately for him he ultimately decides by listening not reading...

First, I do not want to offend anyone, or dispute their findings about improved sound quality through better power cords.  For my system, I have normal Romex electric wire from my breaker box to my plugs.  My brain thinks that if I had a power cord made of this same Romex wire to connect from my plug to one of my components, it would not affect sound quality…it’s just a continuation of the same type of wire.  So do people that promote better power cords believe that a link of better wire somehow filters out bad characteristics, or adds in good characteristics?  I’m just trying to figure out if there’s a theory as to how this works.  On the other hand, I can see that some things can happen without explanation.

@tcotruvo The logic of the “power cords make a difference” argument is that the component to which the power cord is connected experiences the AC it receives from that cable and knows nothing of the original origin of that power. So whatever that cable does to the original AC that is what the component operates from.

An anecdote.  Paul McGowan, the head honcho of PS Audio used Audioquest’s top level power cables on his reference system gear and was confronted with the reality that his system sounded so much better than with PS Audio’s own reference grade cables. From then to this day, PS Audio recommends AQ power cords be used with PS gear. 

@hifiman5   OK, that gives me something to work off of.  I haven’t tried any power cable upgrades yet, but I’m getting there.  I suppose that most component manufacturers have to keep their costs down, so power cable upgrades are up to the consumer.  My speakers and subs are powered, so speaker wire is not a direction I can pursue.  Thanks!