How far have power conditioners evolved?

I think they have improved considerably but the results you will get vary so much with individual conditions that it is hard to predict if you will hear a difference between newer and older. You may or may not need one depending on your AC quality.

i think it is necessary to distinguish between parallel and serial conditioners.

i have experiemente with active and passive conditioners in which components do not make direct contact with the conditioner. there are two types. the first is something which plugs directly into an outlet the other is a product that cois placed somewhere on the component. the latter are more recent in development and may use materials which were not used , say during the 90's.

as stan connotes, their effectives is not predictable. sometimes it is worth the time to try them.

quality of ac and your general satisfaction with the sound of your stereo system are salient factors.

notice, i have excluded serial conditioners, ie.e, those which interface both the component and the wall outlet.

there are so many of them it's impossible to recommend one, assuming you need one.

Same as ever? Elizabeth, such a statement implies either your system lacks resolution to hear the benefits of some of the great PC units out there, or you have not tried them. But they are hardly the same as ever.

Many must be tried to determine if one brings on an improvement to the system. Some can and do make a huge difference to many systems, even those with dedicated lines such as mine.

People that have only tried a few or budget-priced units should not make blanket statements about the performance or relevance of PCs.