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

I bought new an expensive(for me) well known and reviewed power cord for my very good amp and plugged it directly onto the wall socket. 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? Before I get the snake oil answer I want to let you know that I bought an upgraded cord for my pre as suggested by the pre’s manufacturer and am pleased with the results.

I guess for full disclosure the amp’s manufacturer said don’t bother. But I had had good luck with the pre so I thought it would be a good idea.

Anybody else have this happen to them?