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

<knock, knock> 

"Who's there?"

"Reality"

"Reality who?"

"The reality that bit you in the butt when you got suckered into an expensive power cord"

The point is to improve the signal at any point in the chain before it reaches a component. So a better outlet and power cord makes perfect sense. This doesnt require much imagination. 

My opinion, if you bought a quality product, the manufacturer has engineers that designed the power supply for the amp and know the maximum power draw the large electrolytic capacitors draw and the power supply maximum current in order to meet the designed specifications. My Primaluna came with a large gauge conducter. (Large diameter cord) I am sure the cable is copper, not gold or silver. I am not going to be judgemental in saying you wasted your money. I think if the $500 cable makes no improvement as claimed by the manufacturer, then they should honor a refund if they are a legitimate company. I feel bad for your situation and hope you can get satisfaction from the place that sold it or the company that made it.

Power cords have no effect on audio quality.

I would be curious if you did a blind test and could hear the difference.