Are manufacturer AC cables good enough?

Not good enough for me. They're functional and that's about it. Any after market power cable I've switched to has been better than the stock. 

If people like their stock, that's great; they're the ones listening to their system --- I'm not. Same with people who make fun of any power upgrades I make --- my system, my ears, my money. Not theirs. 

@thyname the people who consider power cords a waste should be very happy that they don’t / can’t hear/ make any differences. Congratulations; they have reached the end of their audio journey. They can spend their money on other fun things like records or the house mortgage or a car or their kids’ college.

But when the rubber hits the road, those people aren’t there at my system, in my house, and have no vested interest in my system, other than to tell me what I’m doing is a waste of time and money. And why do they care so much what others do with their money?

If anyone doubts or wants to know if a cable makes a difference, then they should buy one and return it if it doesn’t. However, the naysayers have a MASSIVE problem with this and REEEEE anytime anyone brings up using their own ears and forming their own experience. "Blind believe what I tell you, don’t trust yourself, only I am with the full knowledge."

Honestly, this whole argument reminds of the "DACs are DACs, Amps are Amps" argument. I mean, for those people making that argument....look at where you are. Look at the site you're on and who it appeals to. Look at the site you're on and then look at the pricing and inventory offered. The irony is hilarious.