The remedy for dirty power is depending on a) the time of the day b) your system itself (they are noise generators themselves and cross contaminate throught the grid) c) the rest of your household equipment d) tha hood you are livin in. If you have a lot of wall warts and computers for example on the same spur as your stereo, you can start with placing them on a separate spur and filter them also. They are spitting out a lot of RFI and harmonics. Clean power is not a one stop solution. A good filtered power bar with DC correction will do wonders. But don’t forget good quality cables and connectors, cable dressing (separation) and correct phasing of your equipment as a starter.
Dirty power can be better described as suboptimal power. The quality of the power supplies in every system vary. So some, people hear great differences, some will hear improvements in de last %. Some power supplies have better noise blocking capabilities and filtering qualities when rectifying AC to DC. I don't believe in golden ears BTW. Maybe there is a difference in sensitivity of one's hearing capabilities but mostly it is experience.