Is it all in my head??

Have a buddy play 10 songs for you blind.  Ones that you’re intimately familiar with.  Play each song twice.  Once with the upgraded cord, and another with the stock cord.

Pick your favorite.  If you somehow pick the upgraded cord even 75% of the time as your favorite, well then you’re either fairly lucky or truly can tell the difference.  My guess is you’d guess correctly about half the time.  

Another way to 'think' of the 'last three(six, whatever) feet of power cord is as a LENS, or a set of lenses, that focus the sloppy waveform of the AC into a coherent and better shaped waveform, with a tighter wavefront and less blurriness. Then the endless miles of powerlines menas nothing, as the lens solve the power waveform issues RIGHT THERE!

@prof : I came to this conclusion after hearing the entire system perform as a whole.  When I say everything matters, I mean everything in the room, including the room itself, diffusers, the exact speaker placement, chair placement, isolation racks, (and yes, even the cables).  It seems to have taken everything involved to create the detailed images I "saw" with my ears.  In fact, I couldn't even hear sound from the speakers when sitting in the listening position!  It was as if those speakers weren't making the sound and it was coming from a different dimension right above the amplifiers.  I cant even describe it, but i would guess if you went switching things all around, the portal to where the music was coming from would be closed and the sound would just come from the speakers (if that makes any sense).

Thanks @waltertexas

Again, that’s in incredible sounding system you heard.

As for the type of dimensionality and sonic “dissapearing” of the speakers - that’s something I’ve always favoured myself, and my speaker choices reflect it. I regularly get that effect from my Thiel, Waveform and especially my MBL omni speakers - an amazing dimensional sound field that seem utterly detached from the speakers. It even happens pretty easily with my little Spendor 3/5s.

All it really takes is decent speaker positioning. I tend to have my speakers well out from the back wall and closer to the listening position. Friends, including fellow audiophiles have described the sensation of hearing my systems as “spooky real” and are generally amazed.

BTW, this didn’t take any aftermarket power cables or expensive high end speaker cables/interconnects to achieve :)
Just good speakers and decent care for acoustics and positioning.

Cheers.

Some folks like those MBL Speakers. I don’t. I guess tastes vary. In fact I had the misfortune to be in the exhibit at CES right next to the MBL Room. Thump, thump, thump all day long. I did take the opportunity at some point to go next door to see what all the fuss was about. But I had to leave right away. The MBLs look impressive, I’ll give you that. Would an aftermarket power cord helped? Difficult to say, but it probably couldn’t have hurt. 

Seasons greetings! 🎄