🚀 go-pugleaf

I've got a midi studio set up with a bunch of computers and such.
Anyway, I changed rooms within the same dwelling and I seem to now 
have a horrible ground loop problem when everything is turned on.  
I've narrowed it down to the SE/30, a sound module and a mixer 
all plugged into a power conditioner plugged into the wall.  
Everything is grounded except the mixer which has a two prong plug. 
If I turn the SE/30 off, the problem goes away.  If I leave the
SE/30 on and turn the sound module off, the problem goes away.
However, I cannot have both units on at the same time without 
difficulty.  

I've tried plugging the SE/30 into another wall outlet.  Since it was
on the same circut the problem became worse.

I tried raising the third prong on the SE/30 with an adapter, no
difference same problem.  Does anyone have any oppinions short of
running a line to a water pipe.

Any help would be appreciated. Thank you.

maurices