Has anyone had "ringing" with multiple RGPC units?

After having a wonderful experience with a Richard Gray 400 MKII power conditioner, I added an RGPC 1200 to my system. While experimenting with different ways to connect everything I found that when connecting my DVD/CD player to one side of the 1200 and my preamp/processor to the other half (or to the 400 MKII), the system seemed to ring, which sounded unnatural to me. It sounds more natural with both units plugged into one side of the 1200, or both into the 400 MKII. Has anyone else experienced this? Is this normal? Does anyone know why this occurs? I would appreciate any help anyone could provide.
I auditioned the 1200C and did not hear any ringing but here's
some info: Why pay so much more for the 1200C when all it is
is two 400's wired parallel? So I have two 400's in a daisy chain config which got better results and saved a lot of $$$.
WOW......someone finally responded to my question - Thanks! After much experimentation and after having the same experience with a second system I put together in my study (two channel only), I determined that the "ringing" I was hearing was actually an increase in microdynamics, coupled with a closely miked recording. In other words, the units were just doing their job, and quite well I might add.

As far as why I bought a 1200 is concerned, I got a very good deal on it, paying close to the price of two 400's, plus it looks nice and I can put it in my equipment rack.

Thanks again for taking the time to respond.