ozzy,
I’m not familiar with the Niagara unit or how it operates. However I have looked at the website and I see tons of components, circuit boards and coils. This means it’s almost certainly a different type of line conditioning device to the Puron, and the Niagara obviously does not operate according to my description above, whereas the Puron probably does. I know how passive devices interact, but how active devices interact with passive ones is very hard to predict. I can just say that I would switch to passive devices only, and concentrate on achieving the balance you like by using devices that complement each other. Each electrically active material in a passive device has a band gap that controls the frequency range of EMI that the material can absorb. Getting that balance of materials right is crucial, and if you get it right, you won’t need an active conditioner any more. (unless your AC line is faulty and needs voltage regulation with an active line conditioner).