How did you feel about the change when you first inserted the Power Plant? I'm assuming you did do comparison to make sure there was an improvement before leaving it in the system.
There were times I tried power products and passed. I tried one of the earlier Transparent pieces, I had a Krell amp at the time, the sound was better without the conditioner but I believe it was limiting th power to my amp.
I do use the PS Audio Quintet which has outlets for power amps, it seemed to improve on whatever was plugged into it. I now have my power amp into a Surgex piece. My HT and a few other things go into the Quintet.
More recently with a Pass X250 I tried one of those Audience outlet devices, a dealer lent it to me and all the mags rave about the piece. I did not like the overall effect, it made the sound too polite. The piece wasn't supposed to limit anything, I doubt the effect was due to less distortion, but, if so, I can live with it. Natural music has dynamics and I want that in my system.
I don't think power products for the most part will work the same for everyone across th board, due to variables in gear, in power to the house, in othr items plugged into the homes power circuits etc.
You mentioned a dedicated line, that's supposed to have a large improvement in itself.