justubes2, I see you have been playing with various plugs too:)
Too much Ansuz on the stereo ac line can make bass too heavy in my experience, especially the older version of the Sparkz. Their new Sparks TC3 is much better than previous generations. But they are very effective noise killers, and the older versions work very well also on other power lines. I have both TC2 and TC3 plugs in my home theater also.
For Nordost QWave/QSine/Qv2/Qk1 they also are good on other lines, but I think they are products you typically prioritize to have on your stereo ac line. And here I prefer to have as many as possible of them. They do no harm, only good. Same with ADD Powr, especially the bigger units, but some of their plugs work well on other lines. And the same with Telos QNR and Macro N. For the Mini-Q I find it better to have them on other lines since they are not quite in the same league as their bigger brothers.
I have put ADD Powr Symphony Pros where I earlier had Nordost Qx2/Qx4 so the Qx2/Qx4 units I have are no primarily serving on other lines. I have them on both my refrigerator and freezer where they do a really good job:)
I am familiar with the HFC helix plugs. I have plenty of them and really love them, so what you say about Puron sounds very promising - and tempting! I found a US dealer who could deliver with Schuko plug. We´ll see...