I'm having a really hard time with: "Power cable reduced my soundstage"...

Tone and soundstage are two very separate performance characteristics IME.

The academic studies of psychoacoustics better explains the difference your friend claims to hear - more so than any quasi-technical explanations you’ll find littered throughout the web and this forum.

The only ways a power cord might affect the sound is if it either, a) restricts current (increases resistance) to the point that it limits the amplifier beyond its maximum current draw capability, or b) its shielding is different, thereby causing an increase or decrease in the total EMI of the system. These two scenarios are both uncommon.

What is most likely is that your friend expected to hear a difference which affected his/her brain chemistry (altered mood) which led to a real perception (not necessarily reality) of difference. That’s about as close as a component can get to creating "magic." Remember that all magic is an illusion.

The same phenomenon occurs when one listens to their system while fatigued, or following a stressful day.

captbeaver writes:

My good friend that is in the business and very very knowledgeable calmed that a well made 10ga power cable reduced his soundstage... I’m not saying it will or won’t but why would it? I would like to know the science behind this. I did research on here but not satisfied. I had a pair of Logans and they were wonderful and I used stock power cables and the stage was crazy... I have been making cables for years ( musician ) and know the value on quality... what is the magic?

First of all if this is true I would have to question how "very very knowledgeable" and "well made" and "reduced his soundstage" can possibly go together? Well made would not reduce, and no one with even a little knowledge would claim this. They would say this terrible piece of crap cable reduced my sound stage. So right off we have a puzzle.

But that’s nothing compared to the puzzle of "why" power cords work.

Solve that one and you got a whole pile of money just sitting there for the taking. To even begin to get some idea just look at Ted Denney III, the man is rolling in it, and even he isn’t exactly sure and has to keep constantly experimenting to find out.

As for me, I could pretty much care less. But not much less. It would be nice because if you knew then you could look at the different designs and not waste your time on the bad ones. But nobody knows. So no choice but to go and listen and see what sounds best.

If there’s magic to be had, and there is, this is the only way I know of finding it.

Second of all... it is true. 

Ok
1 He is very knowledgeable.

2 The cable is certainly well made.

3 Compared to a couple of high end cables he own’s  and reps... the sound stage was reduced.

1+2+3= go together

he was kind enough to take part of his busy life to test my cable against some big boys... he is going to keep it for a month or so to burn in then test again.

In my experience, shielding tends to close in the sound (although some system really need it).   If with this new cable (op) the soundstage is reduced it could be that some hum is coming through and screwing up the perception of "air" and "placement".

I’m pretty sure shielding can’t deal with the rf coming in on the AC line. Or with the rf generated by microchips, among other things.