New expensive power cord for amp and no change in sound?

 After a couple of weeks of daily use I hear no change in the sound quality from a $500 cord. I don’t want to name it for fear of getting my thread deleted. You would know it or at least be aware of the company. Did I throw away several thousand dollars?

. . . and am I misunderstanding you? It reads to me as if you once replaced the OEM cord with a $500 cord and then recently replaced the $500 cord with one costing way more than that?  Or have I got that wrong, and the upgrade that you just made that you are hearing no difference with is the $500 cord?

"the amp’s manufacturer said don’t bother. "

If anyone should know, it's the manufacturer?

an amp I bought 2 years ago came with an expensive power cord (as a gift - the seller was getting rid of everything). I hear no difference whatsoever between it and regular power cords. I assume it depends on the components, if my amp and speakers were in the same class as the cord, I might hear the difference. 

If power cords really made a big difference wouldn't component manufacturers be putting better stock cords on?  Are there any component manufacturers that put anything other than standard plastic covered cords in the box?  

"I hear no change in the sound quality from a $500 cord"

"Did I throw away several thousand dollars?"

How does one throw away several thousands on a $500 cord?