Two audiophiles walk into a bar. After a couple pints, they start to argue over whether silver or copper headphone cables sound better.
To settle the debate, they start to ask bar patrons to do A/B listening tests with their portable setup, and vote on which one sounds better.
None of the bar patrons can tell a difference.
They go next door to another bar, have another few pints, and repeat the exercise. Nobody in the next bar can hear a difference, either.
They go to two more bars, end up stupendously drunk, and harass another few dozen people about the difference between silver and copper. Nobody hears a difference.
They stagger out into the street, still arguing, not satisfied with the conclusion. One of them stumbles, is hit by a car and dies instantly.
He finds himself face to face with God himself.
"Lord, this might sound strange, but I'm wondering if you can settle a debate I was having when I died. Do copper or silver cables sound better?"
"My son, there is no audible difference in these headphone cables."
The audiophile is elated. "I knew it! I DO have the best ears!"