What difference do power cables make?

As for power regenerators, I'm always recommending caution.  I just purchased the predecessor to your PP12--the PP10.  The PP10 is 80 lbs of copper and heavy circuitry.  It does not limit current to the amp and I have my amp plugged into it.  Your pp12 is probably the same.  However, I saw a thread where someone asked Paul McG about PP10 vs PP12 and he did say the PP10 doesn't have all the cool new features of the PP12 but may be slightly better for an amp.  I can say that I am very confident that the PP10 does not limit the amp.  PS audio power plants rectify the current and then invert it.  They have one hell of a quality inverter.  

The PP10 has an IEC connector so I use a 10 awg generic power cord to feed it.  I have a dedicated 10 awg circuit that I installed in my wall.

The PP10 has a built in Oscilloscope.  It is measuring 5% thd most evenings on teh power coming in.  

Jerry

+2  @steakster / @facten    Some will always believe almost everything in Hi End Audio is "snake oil" a 40 year old Adcom amp with some repaired Goodwill 12 inch 3 ways is near SOTA!  IMO fear is holding most of them back which will forever keep them in mid fi purgatory.

None

@dayglow 

Vinnie Rossi is a US  manufecturer.

OP, I'm a relative novice here, so here's what I am sure about:

I have put in dedicated lines. This, I am certain, is the most important thing to do.
I have hospital grade outlets.
I have a decent Adept power conditioner, power strip, and a shunyata defender. All purchased used. This was the Almarg setup and he knew what he was doing.
https://audience-av.com/conditioners/ar2p/
 
I purchased cords from Pangea, used, which are appropriate gauges for my gear. 9 gauge for power amps and 14 gauge for front end. They were not expensive, relatively.

Do I hear a difference? I am not sure, but I know that I have at least done the minimum for my system in terms of the wire thickness and shielding.

Down the road, I may try:

(a) a regenerator
(b) more expensive power cords

but until I know that everything else worth spending money on -- room treatments! -- is done, I will not return to the power cord issue.