I have the Purifiers soldered to each driver in my system, and on occasion burn in the plug & Play units on my system as well. So in effect, I am probably doing the same "double Bybee" thing. It does make quite a difference. BUT on some recordings, subtle musical elements already in the rear of the stage get pushed too far back for my liking, Its almost like along with the noise, the extra Bybee takes a wee bit of the music with it. It gives the illusion of taking only a selective part of the music, in that the highs are not rolled off or the mids more subdued, just cetain elements get pushed further back.
That is just my experience, your mileage may vary...[/i]