Interesting look at THD

Yes, it and they are very interesting to look at!

Read it twice earlier.   Didn't see anything applicable to audio, regarding the industrial, "remedies" mentioned.   I must have missed something.

You do understand that the article concerns Variable Frequency Drives and Power Factor Correction problems, in an industrial/Three Phase environment, rather than audio, right? Just my opinion, having worked in that, as well as home and pro audio, but- I’d say apples and watermelons.

If you're concerned with noise on your neutral or ground and actually want to test for it, some years back there was a discussion regarding AC line noise and conditioners(https://forum.audiogon.com/discussions/analyzing-the-power-from-the-outlet), to which I replied, " This is a device that can be plugged into a dual-trace O-scope, and will display the high freq noise, on your incoming AC(both line to neutral and neutral to ground): (http://pdf.textfiles.com/manuals/STARINMANUALS/ETA/Manuals/Power%20Probe.pdf) Here's a demo of it's display and the noise on an AC line: (http://www.youtube.com/watch?v=vOO89uHEprM) There are three parts to the demo on Youtube. Of course everyone's AC quality varies, depending on what's connected to the their local source(everything operating on your side of the neighborhood's single phase distribution transformer). ie: In your own home; anything digital that's operating is polluting your AC with very high freq noise."