rmassey,

Not to belabor the point (just trying to help), are the two subs plugged into different circuits? As I understand it, ground loop arises from a differential between two different ground potentials. Thus, plugging two devices into one phase on one circuit avoids that risk, but two different phases or circuits introduces the risk. I sure hope the problem is not that use of one balanced and one unbalanced input introduces that risk because that is precisely what I had planned to do. Let us know how the splitter works out.