dual cathode follower problem

[piano3]

217 may be legal and they were certainly careful to battle through the snow on a morning when most people were struggling to get to work in order to do a measurement at a relatively non peak time and shut me up.This area is notorious for supply problems. 210 or less than 200 is certainly not legal- 213 or so is a common reading for me. Yes,signal and safety meet at phono,ground lead connects to screen and the adaptors are professional Neutrik ones so I assume that all is ok with these.The circuitry is totally differential up as far as the power amps. Also, as I mentioned earlier,if I monitor any of this through headphones when connecting to my pro. DAT recorder which I assume is double insulated there is no problem whatsoever.

 

[DF96]

You could ask them to leave a voltage monitor in your house for a few days. Or do a 'voltage diary' yourself and send it to them.

I must confess I am running out of ideas about your hum. Is all the equipment run from the same set of sockets, so they are electrically close to each other? Do you have a sub-station next door, which might give a big magnetic field? (My sister has!)

 

[piano3]

We have a major rail line fairly close by but I would hope that they are on a completely different circuit ! I think the idea of keeping a voltage diary is a great one;followed up by a letter rather than a pointless and frustrating phone call. The only wiring in my house that is suspect is the lighting circuits; the ring mains were replaced by my father who is an engineer (a proper one,I mean,from the days when a PhD. and university research actually meant something). Shutting down the lighting circuits makes no difference. You have been extremely helpful and patient and my ideas about this grounding topic are very much clearer now. Thank you very much.