I am indeed not talking about power supplies, which can make a difference. I’ve seen products that have power supplies restrict their performance as the amp modules were capabale of more wattage than the power supply could offer. And thus, since more wattage means more dynamics, I agree with you on that point. Not so sure I agree with over-engineered and rated for more than what is needed; like I suggest more wattage for power amps that what is needed as most amps have more distortion at the top of their range and more heat dissipation which can reduce its lifespan, but if an amp didn’t have those issues, then I wouldn’t reocmeneded more wattage than necessary, same goes for power supplies, now I don’t know if the power supplies aren’t as good when you get close to their limits, if they do, then yes, get a better one that what it’s rated for, though I would argue what it’s rated for is thus incorrect.
I am disagreeing with the fact that changing the power cords can make your bass deeper and give you a wider soundstage.