The better a component is the more evident a power cord and fuse change will make.
I see what you are saying, but I think there are some other things worth noting...
In terms of raw
power, electricity is a medium, as is water or air. But regardless of the medium, if it's tainted to begin with, that which consumes it will be affected by it. So if you were a criminal on death row facing the electric chair, it might not be a bad idea to insist on the grounds of compassion that the power be conditioned to the highest possible standard for a cleaner death. Seriously! But that's another discussion.
The point here is if you're tapping from a dirty power source, you need a filter. Is that what boutique power cords are designed to do? Drinking tainted water or breathing in tainted air is not a good idea. Either one could make you very sick or even kill you. The quality of electricity matters.
Many people prefer to listen late a night because that's when their system tends to sound best. The reason is there is a lot less activity and draw in the electrical grid, so the power is actually cleaner than it is by day.
Getting back to power cords and fuses, I think it makes more sense to invest in cleaner power than boutique power cords. Fuses however are different in the sense they are designed to protect the electronics, not filter tainted power. Haven't tried one yet, but I'd like to try one in my DAC-10.