Thanks both - got it now, already considering how to get a suitable transformer for a home brew version - don’t worry, I’m safe with electrickery, have been doing it since age 10 (when I blew the house fuses experimenting) and have been properly trained in it twice in one job or another, I just wasn’t clear of the layout wrt to audio electronics 
UK mains is a little different, but the principle still applies.
(and I hereby indemnify you all against any issues I may encounter!).
My Noise Harvesters are dead with not one flicker. People come home and from work, turn on their gadgets, and wham!! All 3 are like strobe lights. I’ve put electrical tape just so I can see them working. I have a Duet Power Center PS made years ago. Passive and active. 2 outlets, balun and 2 CariX2 and 8 more numbers capacitors designed to filter RF/EMI. Balun a passive magnetic wheel where hot and neutral wires are wrapped in opposition to magnify the high frequency noise out of phase. The stronger the crud, the stronger the cancellation. So I got one headphone amp plugged in with 3 Harvesters surrounding it. The DAC is powered by USB with a iFi iSilencer+. I had a P300 Power Plant years ago. Only power DAC’s, transports, pre-amp, phono stage. Had a Pass Aleph 5 60W stereo. Single-ended Class A. Burned 300W idle. B&W Nautilus 802’s.
I read the following statement today:
“The Noise Harvester is the world’s only device that actually eliminates line noise from the home’s power lines.”
This seems a superlative used by pure lack of knowledge of other applications existing in parallel. I think such pretenses should be used more carefully.
E.g. this is a series of products I know, doing (among others) exactly this, probably in an even more sophisticated and stronger way, also for the power grid.
Anyone have a dedicated 20A line for their audio system and still use noise harvesters on other lines (other outlets in room)?
Me. I have that situation happening at this very moment.
Ditto, 20A line (actually 2) going into Audio room noise Harvesters (3) in various locations that connect to the same panel that runs the room. I had them figured why not.
Out of curiosity, do they blink regularly? And does it seem to be in conjunction with any other electrical activity in your room or the house’s other rooms?
Mine may rarely blink, blink regularly, or go a bit nuts. I have not been able to definitively correlate the behavior with anything.
Good to know. I was thinking about the question and about whether there’d be any benefit to that use case
Mine blink like crazy when my girlfriend is in the room. Don’t know why.
That’s exactly what I see with the 5 I have of them. Not a blink, blink more or less regularly but randomly and then the dread it looks like they’re having a seizure with a very rapid, machine-gun-like series of constant blinking that can sometimes last minutes but usually just for about 5 or 6 seconds.
I have 5 on my 20 amp circuit. They blink occasionally, not in concert nor with any recognizable patterns. They all go crazy while the oil furnace (in another room) runs.
Not much blinking unless I have a small desktop fan running, that seems to set them off. I don’t really look at them much as they’re not in my sight from my listening chair or my desk. I just let them do their thing and hope it helps
I can’t remember who did this but there was a video on YouTube where someone took an analyzer and tested the Noise Harvester and found that it didn’t do much. I’ll try to find it, hopefully I’m not crazy and I’m not imagining things.
To set the stage: I live in apartment that’s part of a development with 16 two-story buildings with each building having 14 units.
I think most of the noise I’m seeing (and the Harvesters are in my direct line of sight) do not react to the refrigerator or the central A/C going on or off. They may contribute to the general background noise but they’re on other circuits for my apartment. The one thing that sets all of them off blinking a single pulse in unison is turning on my TV which is on the same circuit as the NH and my stereo.
Yes. I have a couple in the chain. I also use the ifi AC defenders.