Isolation Transformers

[Maxwell_E]

Haha, only background music whilst cleaning. That's nice, cause I don't have any digital equipment, so only on transformer needed.

Grainger, when you say you have them on different 220V lines, are you talking about at the breaker box? Wow, that's some dedicated wiring.

[Grainger49]

Yes, the breaker panel is 220V AC incoming.  Alternating breakers are on different legs to ground, i.e. 120V to ground or 220V between the two high legs.

It is typical of such distribution panels to alternate between the incoming phases to try to balance out the load.  I had 20A circuits pulled with #10 wire to dedicated outlets in the listening room.  That was a whopping 25' from the panel so it wasn't hard or expensive.

[richardl]

They are effective at removing noise from the power line.  they have the most effect on the smallest signals IME.  Also, your amp has a reasonably large power tranny in front of it so adding another tranny in front of that can be pretty marginal in effect.   the Power Conditioner should help if it is hospital grade.  Some other commercial type power conditioners add noise and therefore are not much help.