When you get a lot of linear (i.e. not switched mode) power supplies working together, the perfect sinusoidal mains wave doesn't stand a chance. Every Linear supply has a switch on of 0.6 to 0.7 Volts away from zero potential (i.e. neutral level) therefore these devices ignore the first 0.7 Volts of the sine wave as it oscillates about 0V and only start conducting after this has been exceeded. As the sine wave makes this osciallation each side (+'ve and -'ve) of zero potential (neutral), this will occur 100 times per second for full wave rectification. Virtually everything that uses an internal DC supply works this way. The poor old sinusoidal waveform doesn't stand a chance, and that's before the local cabbies and your fridge radiate RF onto it etc. etc. etc.
Therefore technically a mains
re-constructor is the thing to have. I say technically.......... The last one I played with was £14k delivered to you door, not only did it reconstruct mains, but it allowed you to add your own noise harmonics to it if desired, in all sorts of fancy ways. I think it was 10 Kilowatt too, so even WM and GrahamN shouldn't be able to use up
all of it's headroom

. Lovely piece of kit. I only wish I'd thought to try my hi-fi on it. Oh, and it was the size of a small fridge, and seemed to weigh the same as a small car when it had to be moved about.........and noisy

.......all those fans.....
As for the merits of using one on a hi-fi? That's best left to your ears. One thought though, only Linn and Chord think it's advisable to use a Switched Mode power supply in their amps, everyone else shys away from them for many a good reason, and it isn't cost (it used to be reliability, but not so much these days), everyone else has stayed with the aforementioned linear supplys.
Now a mains re-constructor, well that's the biggest switched mode power supply you're ever likely to see, and then for luck (and to make it work), it re-assembles it all again. From my experience, the "perfect-ness" of their reconstructed sine wave depends on the load, but I expect a Hi-fi orientated one has got around this. Now you can argue that the switched mode bit is in a seperate box, and so radiated emissions should be minimal, and as mains reconstructor by definition, conducted emissions should be zero. But would you be able to sleep at night worrying about it?
Even if it all works fine, I'll wager that the majority of your kit you're going to feed with it, will have a linear supply in it. I think I've gone full circle now



Cheers