A certain online retailer asked me for a review of Pangea power cords..

An interesting comment about destroying (ruining..) the last few feet.I own a lot of Pangea, but do still use a few ordinary home made sets of power cords.
In my acquisition and installation of a pile of Furutech duplex, and a few Furutech plugs, I then realized the previous brass (Wattgate) plugs used on some powercords, if reinstalled, sounded terrible. The brass gave a sort of background velvet buzz in the upper midrange. Easy to spot once I noticed . With brass plugs, buzz, no brass plugs, no velvety buzz. (this with no brass in the duplex. Furutech is pure copper,the ones I bought plated with gold or rhodium, with springs for grip)
Another thing which reaffirms the idea of ’damaging the last few feet:
I use a pair of 32 ft long, and 41 ft long (I extended the prior 37ft) the 41 to a ’on floor’ twin duplex box for the amp, the 32 ft to another on floor twin duplex box for the two conditioners. The wire in those extension cords is a dual Quad of MilSpec 12 gauge silver plated Teflon 600v wire. As used for extension cords, they really do not affect the sound. (Though many say silver plated copper tends to a bright sound) BUT, big BUT, if (As I did try) to make cords TO THE EQUIPMENT of the same wire, using rhodium Furutech plugs. The wire DOES SOUND BRIGHT. I really just had to swap the plugs to some OFC wire I had designed for AC powercords and then the sound is great. (same Furutech plugs on OFC pure copper)
Wat this EXPERIMENT showed me is that the only part that really matters is the LAST FEW FEET.*(* aside from the usual need for large enough gauge wires prior, to allow current to pass easily)

sleepwalker65Could one of the folks who endorse upgraded power cords please explain: how a 6ft “upgraded power cord” could best a run of the mill 14AWG or 12AWG power cord, when there is several dozen feet of pedestrian Romex wires through upstream 59 cent receptacles is in the path to the breaker panel?

You're assuming facts not in evidence. I use 20A dedicated lines comprised of 10AWG NM wire. There's not a 59-cent receptacle anywhere in sight.

Can anyone explain to me how the last few feet of a power cord makes a difference when the rest of the house wiring is standard Romex copper wiring ?

Oh, silly, Reddi Killowatt believes size matters. 🐍💩

Here’s the thing about power cords and interconnects. Beyond a certain level of build and materials quality, they do not get better as you spend more and more. They just sound different. So if you’re assuming that a decent Pangea cord will get killed by say an Audioquest model that cost ten times as much-- sorry, you’ll just be hearing the differences based upon your unique setup and environment and nothing less or more than that. If you think those differences are worth it then great-- but to say the sound is better or worse is just an aesthetic judgement-- i.e., you like the change/differences.

A lot of the claims made by companies selling super expensive wire are pure hokum. You buy their cables, hook them up, and you get a "different" sound or sonic signature-- and you’re very much more likely to say that sound is "better" because you paid more. COnfirmation bias is a very real thing-- proven countless times in experiments.

If I were to create an experiment where we let a group of experienced audiophiles listen to tracks played on a very high-end analog or digital system, and then switch out the cables and repeat-- so long as the sets of cables we used ranged from very well built quality cables all the way up to insanely expensive cables-- I would bet that no one would be able to rank them from least to most costly based upon various sonic "improvements" made to the system (claims that many mfg’s make all of the time). Everyone would probably hear differences and have opinions about those differences-- but NO ONE would be able to tell a $300 cable from a $3000 cable and then rank them all based upon cost.

Often, changing cables is a give and take experience. Some elements of the sound recede while other characteristics become more dominant. You gained some AND you lost some. All that really matters is whether or not you like the change, and your opinion might change over time as you get used to the changes.

So just buy the best cables you can afford, quality materials and build matter a lot. Listen to them for a while, and if you like the change(s), keep them and enjoy them. Do not assume that by spending a LOT more you will get a "better" sound-- you’ll get a different sound-- that you may or may not like.

Try not to confuse different with better. A $500 bottle of Cabernet does not taste better than a $75 bottle-- both are probably going to be excellent-- and they will be different in character-- NOT better than or worse than. Spending beyond a certain point gets you to a level of quality where what you’re looking for are sound characteristics that you like-- nothing more. There’s a hell of a lot of snake oil out there-- and many times the claims made by some of the mfg’s are a sure sign of this. Try not to be taken in by their wild-ass unprovable claims and just enjoy the music.