Least expensive plug-in power conditioner that works

While I think a lot of these AC issues have local environmental elements that may determine effectiveness and the right components to help, I do own several iFi AC purifiers, including those that came with the iFi Powerstation, and they made a real difference in my home. 
The AC Purifiers helped bring greater depth, greater air around instruments, and even (and I was really surprised with this) added a bit more natural tonality to instruments. 
They are not that expensive and are available on Amazon, so they might be worth trying one or two in your setup.

@dekay Furman has an excellent track record with post outlet line conditioning. Their conditioners are used in hospitals, music halls, studios, and laboratories because of their effectiveness in identifying and neutralizing interference.

My house was rewired to the highest spec before I moved in, and the Furman gives me dead silent power. I chose all my audio components to have inaudible levels of noise. Anyone who has a line noise problem or current instability would best spend their money on wiring and an inexpensive Furman unit. Good wiring has other benefits, including safety and uninterrupted delivery. After carefully determining that none of your components is at fault, consult an electrician to determine the source and extent of the problem.

The only problem I ever had with hum or static was when I added a French headphone amp to my system. The unit was not properly modified to reject 60hz RFI, coming from Europe where current is 50hz, so it was picking up RFI from my dimmable fluorescent bulbs. When I turned them off, the hum diminished to a much lower level - instant-on bulbs have a low standby current. Having determined the culprit, I returned it, and the system returned to silence.

Fortunately, my audio dealer is a "let's solve your problem" not an "I can sell you something expensive to fix your problem" sort.

Audience Forte V8

very little filtering going on but does a great job. 
Good luck Willy-T

phillyrover:

The PST-8 was mentioned by Erik Squires (sp?).

It is the least expensive model (within the Furman line) he recommended.

DeKay

I have been using the PST-8D for about 6 years now on which the "Protection-On" LED is no longer is on. Called Furman and no way to reset it or protection from it.

So I am looking to purchase a new one.  I don’t suppose anyone has owned the PST-8 and PST-8D and has noticed any difference (improvement) in their sound quality using the slightly more expensive PST-8D with its supposed higher level filtering?

Thanks