Thank you Clark for your comment.
Unfortunately, I think that you missed the point. It is possible that a power cord can change things. The description „better“ is a moving target however. Let us take for example a „full range“ driver in a backloaded horn speaker. Most will have deficient midbass and a cutoff of around 50 Hz. Can we talk about „better bass“ in this context? What extension and or qualities do we need to talk about better anything? What reference points allow us to determine if something is „better“ or just „different“. What is the difference between an opinion formed superficially and a fact?
In this case, a claim is made. No reference points were discussed (what WAS the change, in what context, are we talking about ULF/LF/midbass/upper bass or just their overtones). What changed in Amir after the new experience?
As far as short term comparisons go, I am a professional trumpeter and have been playing at a fairly high level for well over 40 years. One would think that I could pick up a new instrument and immediately declare its „qualities“. Reviewers actually often do this. It simply does not work. Sure, there is something that you notice, but after a couple of weeks or months, that „opinion“ changes because the context changes as you get into the instrument. Why? The same reason as I call this particular instance voodoo. What happens when we learn to listen is very complex. The information provided by only two speakers (or a trumpet)is „deficient“ in many ways and we learn to fill in the blanks through experience (well, some learn to fill in the blanks, others keep changing gear and NEVER develop any reference points). If we change something, we have to spend time to overcome the listening habits first. Even then, a „rating“ is often a very stupid thing because there is no free lunch. Even if we would fully understand all of the physics applied to a new trumpet or power cord, we still are not closer to a better experience until we learn to leverage whatever something does. That takes time and a serious approach.
In the case of a trumpet, the same instrument changes its playing quality dramatically depending on the environment. Playing outdoors makes the instrument play in a stuffy way. A nice concert hall gives me better feedback - everything is easier to play. For outdoors I pick a lighter weight instrument that gives me more feedback.
In the case of a power cord there are many things that COULD cause a „change“. Is that change bias confirmation? Is it initially more work for the brain because we have changed something? Should we have noticed the deficiency before? Have we given due attention to phase, plug quality, environmental issues (a certain length of wire can also be an antenna...). Are we noticing a crappy power supply? There are many further questions that must be asked - and even after this we still ONLY have a difference - not a qualitative measure.
I disagree with Amir that better ears hear faster. In my world, the more that I know, the more that I realize what I do not know. Good/better/best NEVER come up. Changes can show up and I can evaluate them and describe the differences and the context. Without the reference points, „better“ is just audiophool jargon. There is no credibility to those without process. They flap in the wind and tomorrow they find something else „magical“ but offer no value add because the experience is never qualified.
For the most part, I keep Analog cables and interconnects as short as possible to limit capacitive, inductive and reactive behavior. Shields are well earthed and I am anal retentive about checking for proper orientation of the power plug in the socket (in Germany we have no power line phase protection. The Schuko plug can be inserted at 0° and 180°).
Whenever I feel blue, I start breathing again.