@yyzsantabarbara Thank you for the additional info, however on a conceptual level I am still confused. I may just be missing something obvious.
How can fiber constitute a "moat" when it is merely a conduit without filtering abilities of its own? If a noisy signal enters a fiber run, isn't it delivered identically at the other end, noise and all?
And if SFP fiber does in fact erect a "moat" protecting a system from noise, why wouldn't coaxial and toslink do the same?
Fiber won't pick up noise along the way like copper might, but what about the noise that entered the signal upstream of the first endpoint?.
Fiber audio networking is new to me, so these may be stupid questions. If so I do apologize.