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

To Eric squires - thanks for the link to the article on power conditioners and their benefit for a Stereo System. I just had to send my Krell S550i in for repair - the main processor on the main board burned out. I use a Furman Elite to protect my Stereo from voltage surges/ noise etc. we had a power surge due to lighting. The system kept playing fine - but my digital display ‘went blank’. Other than this all the electronic equipment plugged into the Furman was fine. I pulled the Krell to send it back for repair - upon removing the power cord (an ANTICABLES power cord ) a hunk of the insulator was fractured and fell off. I should have both the Integrated Amp and power cord back this week both repaired and ready to go.

The Furman saved my butt. I will be adding another Furman to my ‘second stereo system this month.

Michael, I’m certainly not trying hide my system or the fact it’s a Sony Walkman. In fact I mention it quite frequently. 🤗 Your “low mass system” approach helped inspire me. Kudos to you! Maybe you’re just sore I took your approach to the extreme. As I’ve tried to point out to you many times, there are a great many advantages to a very simple battery powered system, none of them actually have much to do with mass. No offense intended. I can always tell when you’re upset and trying to put me in my place. That’s not really an effective way to participate in this forum, at least not with your humble scribe, if you don’t mind me saying so too much.

Power cables have zero influence on sound stage.

Power cables can inductively couple with other cables. This will cause noise from other cables EMI fields to be transferred to the power cable in question. Similarly, when inductive coupling takes place, the EMI field of the power cable in question is transferred to other cables. 

Much of this inductive coupling can be mitigated by isolating (not bundling) power cables from other (power and signal carrying) cables.

When isolation is difficult or impossible, the use of ferrite beads can isolate the noise source. This is why switch mode power supplies have ferrite beads on their input and output cables. 

Shielding, when done properly, can be effective. I say “properly” because most unbalanced audio cables use the shield as a signal-bearing conductor. This causes induced noise to be brought directly into the signal path. The correct way to shield an unbalanced audio cable is to add an additional layer of shielding which is isolated from the signal-bearing conductors, and tied to chassis ground at only one end (preferably the source side). Typically the most convenient place to ground the shield in audio systems is to the preamplifier chassis, as the preamplifier is the hub of the system. 

Going back to the OP’s claim about loss of sound stage, that is due to other factors. Most likely speaker placement and phasing. 

Sleepwalker, you can’t prove a negative. 🤗