The following paper, by Bill Whitlock of Jensen Transformers, presents a good explanation of why equipment connected via unbalanced interfaces (i.e., rca cables) is inherently prone to the kinds of problems that have been mentioned, and presents some approaches to dealing with these problems that do not involve lifting safety grounds:
http://www.jensen-transformers.com/an/an004.pdf
Regards,
-- Al
http://www.jensen-transformers.com/an/an004.pdf
Regards,
-- Al