What fiesta just wrote.If you're using a fancy power block of some kind, it is at least remotely possible that in the power block, each plug or set of plugs is isolated from all the others. If the block is poorly designed, I can at least imagine that might promote ground loops.
Also, "using XLRs" is a waste of money and effort, if the associated components are not internally balanced circuits. If they ARE balanced, then use XLRs, by all means. This issue comes up all the time in this forum.
Also, "using XLRs" is a waste of money and effort, if the associated components are not internally balanced circuits. If they ARE balanced, then use XLRs, by all means. This issue comes up all the time in this forum.