I installed this on my left channel + electronics, plus a P-1800 PF on the right channel. With test track "Deeper" from the album, Transfixiation, by A Place to Bury Strangers, the timbre radically changed in a distinct, repeatable manner. The lower frequencies were substantially tighter and more focused, the mids clearer. A completely different sounding track resulted. Impact on classical & jazz were more modest.

Excellent unit.

I used to have quite a bit of hum in my setup (guitar preamp -> effects processor -> pedals -> tube amp), and I have used other Furman AC conditioners without much luck. This unit finally took care of my hum-related problems. A tech I know advised me to get a balanced conditioner for best results, but those are prohibitively expensive. In my mind even $300 spent on a conditioner was a lot of money. I was very hesitant buying it because of the high price and the fact that it's not "balanced" (whatever that technical lingo means), but after hooking it up and hearing the results I think it's worth every single penny. The hum is 90% gone, from what I hear, and honestly I think that the rest of the hum exists in pretty much every tube amp, no matter how clean its power source is. I gave it four stars because it would have been nice to have some LED lights, like its less expensive siblings. To me, LEDs are practical and when you are spending so much money you'd expect to have them.

Bottom line: Regardless of that little imperfection, If you have the cash and are serious about your tube sound, Furman P-1800 PF R is your conditioner. I am very happy with mine.