Wow. Talk to Mike about that.Originally Posted by GoHybrid
You might also check the ground on the rest of your system. (the definition of a ground loop is two or more ground points causing different frequencies).
A ground loop is unquestionably the issue. Now it's just a matter of finding it.[further testing included running off wall AC which yielded zero noise, inverter AC which was almost as good. the P1900 is the only part that seems to want to ground anywhere but where it should.]
Do mean that you still have some noise using an AC inverter? If so then looking at your other points in the system is probably the best place to start.
As far as an isolator, I got lucky and didn't have a problem so i've never used one. The Audio forum is the best place for this kind of info (not trying to run you off, just pointing you where I think you can get the best help).