[Mike Rivers]

Bob Richard wrote:

Yes, exactly. But Mike's response appears to say that it doesn't matter how
I wire the two destination devices; the circuit as a whole will be
unbalanced regardless. Correct?

"Balanced" (in the electrical context) is one of those words like
"square" or "pregnant." Either it is or it isn't. If you have a bipolar
output with equal voltages of opposite polarity with respect to ground
and at the same source impedance, and connect this to a differential
input, you have a balanced connection. If you then tap off the "high"
side and connect that to another input, you've unbalanced your
connection. The reason for this is that you've put the input impedance
of your unbalanced input in parallel with the output impedance of the
"high" side of the source, therefore unbalancing that path.

You might be able to get it back to being balanced by connecting a
resistor equal to the input impedance of your unbalanced input between
the low side of the source and ground. But unless it's very accurately
matched to the unbalanced load, you'll still be unbalanced. However, it
might not be any worse than the balanced connection that you get with a
single ended "impedance balanced" output.

However, unless you're running long cables and have a lot of EMI,
you're better off just treating your source as single-ended and hooking
it to the two inputs accordingly.