|Removing ground loops can be hard---especially when there are computers and networks involved.|
But I think an easier solution is to use an audio transformer to isolate the systems.
Here is what my favorite audio engineer recommends. I love my Jensen transformer.
The ones I was using were from Jensen Transformers
(http://www.jensen-transformers.com). Lately I've been using ones from
Rapco/Horizon (LTI-100) as they're cheaper and have actual balanced XLR