Interesting look at THD

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.

Yes. You need to read well into the article to get to the parts
that I find interesting, relative to audio system distortions and remedies.

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

concepts are applicable but not the application details

Thanks randy.It's the review of concepts I find interesting. Also the cost/benefit graphs.
The way that skin depth of the conductor varies with frequency
also surprised me. (I don't have an EE or similar background).
This business of  voltage noise attenuation appears very complex/interesting. I feel the increasing capabilities/speeds of computers will ultimately allow better analysis of the instantaneous effects of various interactions and give us significant improvements over whats practically available today.