Is it all in my head??

The power to your system comes to it through hundreds of miles of wire owned by the utility company, but what wire you use in the last 2 feet will materially change it? Does this 2 feet of wire "add" something or "subtract" something from the power that enters your house?
The electricity then enters the internal wiring of your pre-amp/receiver and this addition/subtraction remains intact?

Yes.

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.  

@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).