Dedicated line questions...

This is an example of a isolation transformer, step down.  Feed it 240VAC in and get 120VAC out at 2x the current capacity.   https://talema.com/wp-content/uploads/datasheets/MD.pdf   This is not a plug in product btw, this is either DIY or look for an equivalent factory made unit you can just plug in.

@jea48  I see, thanks for the clarification.   

I have read through this post and I noticed some folks here use both lines from the distribution panel.   That is, line 1, line 2, neutral, and earth, such as would be wired when using the Southwire 10 awg, 3 wire.  Since line 1 and line 2 are opposite in phase for North America (and anywhere else where split phase lines are used) that means hum is more likely to occur since the outlets are no longer identical polarization.   If you are using an isolation transformer and feeding it 240 VAC then stepping it down to 120VAC, then this doesn't apply.   But if you don't have an isolation step down transformer, then you might get some hum.   I see the point for 10 awg wire and a dedicated line, but I don't see the point for using both lines without a transformer.   That really is counterproductive.

Speaking of the  Decware ZLC - I see it has line capacitors from line to earth on the secondary side.   This negates the concept of "clean grounds" or "quiet grounds" that some manufacturers use, noting that others, such as Decware, do not follow that concept.   Has anyone performed any comparison tests on this sort of thing?  I'd be most interested in hearing about this.
Most computer / server noise suppression units have caps from line to earth but computers don't listen to music.   I have some commercial ADC noise suppression systems on my stereo system which have the caps, notably more capacitance than Decware's, and I included them in the green energy noise suppression units I designed at work.   But then, green energy doesn't listen to music either!