Hi Al, I've not seen anything that defines a resistance to ground as a standard. I know that you can have some, as long as the circuit does not put current through it.
But I think the classic example is that of an output transformer, as one might see in a Neumann microphone. In this case the transformer is driving the output with its secondary, which is a single winding without a center tap. One side of the winding is pin 2 and the other side is pin 3. Ground is simply the circuit ground of the mic, but has no continuity to pin 2 or 3. IOW the transformer output is floating.
You touched on an interesting point about the load vs the capability to drive that load. I have found that the capacity to drive the load plays a huge role, about 80% but for that last bit of cable artifact to go away the load must be there as well. Flipping the coin over- if the capacity to drive the load is absent, then its moot and there will be cable colorations.
I remember back in the 1990s Stereophile published some letters to the editor from an audio engineer who was basically taking audiophiles and the high end audio industry to task because as he put it 'cables don't make a difference' and its all 'snake oil'. I think Stereophile published the letter mostly because of the humor value as everyone knows that cables do make a difference, but what neither party really made clear is that the engineer was working almost exclusively with balanced cables while audiophiles were using single ended.
