I'm as confused as amirm. This statement does not make any sense.
Maybe you meant to say something different? A perfect situation would be a pure 50 /60 Hz sine at the output of the filter, and there is not a single device that would not work happily with such a clean source.
They would however produce their own current harmonics anyway .
And a clean sine vave source is not the issue really that would work fine , but rather the high impedance source you would have if you actually had a passive filter working down almost to the fundamental ?
Simplest case would be a very large series inductance . You can get a significant voltage drop over the filter . Hence the filter must be designed for the load . That’s better done in the product itself like a classic LCLC filter that some old tube amps have .
I work with AC and DC drive system where the main inductance is a part of the circuit the . In DC drives they are even classified after their voltage drop in our product catalogue 1% or 4% .
Large AC drives can have an active 4Q rectifyer this has an LCL filter in front then ofcourse designed for the load.
My point really is that if the filter makes a significant contribution it must be designed with load in mind IE a part of the product itself .
If you want a clean 50/60 Hz it s time for a power regeneration device of some kind , that sounds expensive to me for not much gain .
Maybe some motor and generator set
i’m thinking rotating power supplies as a very expensive and cumbersome way to do this , but it will effectively separate audiophiles from large amounts of cash ?