> But we don't know what sort of 50V lines it is.

Indeed! :-).
My point also.
The "specification is too vague and too wide to allow of a certain solution.
Andrew has been asked various questions, but has so far answered selectively.
While it's quite interesting to speculate on how things MIGHT be able
to be done, until Andrew gets more specific, preferably MUCH more
specific, it's more an interesting exercise than a solution.

+50/-50
ground/float
balanced, audio ,stiff, hi z , ... ?
speed.
Power / current allowed.
Cost
Quantity.
More ....


    R
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