balanced power supplies: group purchase of iso...?

Power in my apartment is abysmal, and I've tried a number of things to remove grunge from the AC line: LC filter, PSAudio HC outlet, and now a giant 2 KVA isolation transformer.

The iso transformer, a Plitron model, produces balanced AC, and does seem to clean the line quite a bit. I installed it in a rather nice box with a big Classe-style aluminum faceplate and Schurter and Hubble components. I don't know *exactly* what effect it has on the power signal; my next project will be buying or borrowing an old o-scope or a power quality meter on ebay and seeing precisely what each device -- the LC filter, the PSAudio, and the balanced power supply -- does to the AC signal. An obvious and galling problem that remains, though, is that the transformer buzzes.

Toroidal transformers are known for being more efficient than traditional EI transformers, but they're also more sensitive to dirty power than the EIs. A toroid will buzz and complain in conditions of excessive noise, overvoltage, and DC offset. I suspect now, having (hopefully) corrected the problem of noise entering the tranny, that the cause of the buzzing is either DC offset or overvoltage, or both.

Plitron can build, for a price, transformers with "LoNo" technology -- trannys which would be far less susceptible to noise from DC offset. And a custom design could be impemented that would allow for overvoltage. The problem with a new custom design is, of course, cost.

Would anyone be interested in a group purchase of custom-designed toroid isolation transformers? They'd be designed specifically to handle gracefully the major problems found on modern AC lines, and would produce clean balanced output. I haven't yet submitted specs to an engineer at Plitron, but if there's enough interest, we could agree on specs and then place a order of modest volume.