If a power filter is required (and it does!) buy a power filter.Any addition of an active electronic component, never mind how small, will add to the noise level... :) At least a cord add not a noise of his own being passive....Engineering is the art of trade-off...There is always a cost to pay if someone add an electronic component to the gear or to the system....What i say is about active filter, but passive filter is perhaps a good idea... I prefer my minerals and stones.... :)
It cost 1/5 of one of those fancy power cords, but filters much more than 5x a cable.
Yes, i use passive minerals to filter my grid.... With success at peanuts costs...
I will not argue further because adult brain are opinionated and my goal was reach, hi-fi at low cost, and with only non orthodox homemade methods... I succeed... :)
If i had confidence only in measurements the cost to improve would have been way higher.... Happily i trust only my ears and play with the 3 dimensional embeddings of my audio system with my ears experiments guidance only... :)
« Dont ask if it is possible, create it» - Groucho Marx
« It dont take genius, it takes only time» -Harpo Marx