General Asylum: Science and Power cords by Ole Lund Christensen

Some years ago a dealer wanted to show me the major improvement in sound caused by using a new power cord.
I was politely saying no, do not waste my time. But he insísted, and as he was an importantant dealer for my products, well I accepted to listen to a track on a CD, and then letting him change the power cord, and listen to the same track again.

Having a B.Sc.E.E degree I knew that nothing would happen, and he was just victim of the placebo effect and a "snakeoil" cable distributor.

So my brain was trying hard to ignore the message from my ears, I was hearing a major improvemnt of the sound.

But as the truth is more important to me than my pride, I had to admit to the dealer, that I heard this improvement he was raving madly about.

I left the shop, and spent 6 months trying to figure out what was going on.

When the power has traveled 20.000 meter through standard cheap cables and connectors and fuses from the power plant to the shop, why did the last 1 meter cable matter?

One day it hit me hard, it does not make sense because I am asking the wrong question.
the right question is: Why does the first 1 meter matter?
And the answer comes easy: Because the source of the problem is inside the power amplifier, it is not 20.000 meter away.
The power amplifier generates a lot of noise from the rectifier, and
the current in the power cord is very distorted.

So the power cord is an antenna, radiating noise to all other components and interconnects.
So a shielded power cord reduce the radiation, and different connectors and cable designs affect the high frequency signals.

Today all this is standard stuff, which you are required by law to measure to get EMC/CE approval in Europe, and there is lots of laboratories that measure this every day.

So I have learned to listen and consider carefully the next strange idea.