Power Filtering vs Power Regeneration?

I don't know if a 10 Volt swing in 250V is a big swing or not...❓👀
Anybody....anybody....😯❓
The PS Audio seemed to do its job and sound quality didn't suffer...
Did I also mention that it has cleaned up the 'noise' in the supply....not that I was aware there WAS any previously....but the removal of it is impressive...😄👍

That's a 4% total variation in voltage. I'd say its a big deal. I would expect less than 1%. Now, that's considering that the load in your house is constant. If something in your house is turning on/off when you see those voltage swings then it might be a problem with your house wiring and/or you are too far away from the transformer. I see 125VAC at my house. It stays within a few tenths until a load comes on. If both heat pumps are running and other things are on then I see it drop to 122.5VAC. When I power up my monster amp it gets as low as 121.5VAC but never over 123VAC while the amp is on. 120.5VAC is the lowest I think I have ever seen and that was summertime with the stereo on and A/C running. I have a dedicated circuit for it. It pulls about 5 amps idle current and the preamp/CD player, tt pull about another 1 amp. The power transformer sits at the street at the corner of my front yard.

That's a 4% total variation in voltage. I'd say its a big deal.

Then the PS Audio power regenerator should earn its keep...❓👀

4% variation in voltage should be no worries. If the equipment cannot manage that it can be considered to be problematic. It is useful to ask what voltage the equipment is set up for though. If 235V instead of 240V, 250V is boarding on excessive.

It is worth it to see if the PSAudio solves the problem. If so *then* we can conclude that the problem is AC related.

Just for the record: a 'spike' cannot cause the kind of problems described. Neither can the weather, unless its a secondary effect, such as people running air conditioners more and causing a brownout.

Tony, It is most likely that your friend's system was affected by humidity because of the sensitivity of ESL speakers, especially Quads, to humidity. Humidity affects the tension of the mylar diaphragm, AND it also affects the static charge in the space between the diaphragm and the stators. As I recall, Sound Labs have had a lot of problems shipping their ESLs to customers in the South Pacific, e.g., the Phillipines and Malaysia, for this reason. Thankfully, those of us residing in sealed, heated, and air conditioned dwellings in the temperate parts of the US have only minor problems with ESLs. ESLs are also temperamental at high altitude and in excessively dry air.