Axiom Home Page Forums General Discussion Technical Questions EP500 Not working

Not saying that it'll happen every time, or with every piece of gear. But there can be potential between the grounds of equipment using switch-mode PS. If you connect the grounds (which in the case of RCA cables is also the signal path) at just the wrong time (depending on the phase of the power from the wall) there can be quite a bit of voltage differential between the two components. It will equalize quickly through the input/output circuit.

Another reason to like XLR connections: the chassis ground connects first before the sensitive signal connections are made.