Can a well designed rca cable compensate for ground loop?
It **might** make a difference in some cases, due to differences in the resistance of the shield or other return conductor, and depending on whether the shield **is** the return conductor, or if the shield is connected only at one end and a separate return conductor is provided within it.
But in general I would expect susceptibility to ground loop issues to be more dependent on the internal grounding configurations of the components that are being connected. And in many cases also on how AC power is distributed to the components (e.g., from a single outlet vs. multiple dedicated lines, etc.), and through what kind of house wiring it is distributed (e.g., within metal conduit, or with Romex, etc.; see
this paper).
... if balanced is the favoured "vehicle" for long runs ..... why are probably 98% of all xlr cable adverts for sale a seemingly average of 1 metre long? I wanted 8-10 metres but are they ubiquitous?
Interconnect lengths of 1 meter or thereabouts are of course more often needed in home audio applications than long lengths such as 8 to 10 meters. And since most cable parameters and most cable effects are proportional to length, using a greater length than necessary will generally worsen whatever sonic effects the cable may introduce, as well as increasing the cost of the cable.
I would say that the short answer to most of your questions is simply "it depends." And unfortunately many of the dependencies don’t have much if any predictability.
BTW, you may find
this paper to be of interest, although it deals mainly with pro audio applications. I’ll quote two sentences from it:
So why doesn’t everyone do it [the right] way? Because life is messy, some things are hard to change, and there will always be equipment in use that was made before proper grounding practices were in effect.
Regards,
-- Al
