AC coupling capacitor in the ground to break the ground loop?
The whole circuit you provided is a single ended AC coupled to the differential output.

1st stage buffers (x -1) then the output is AC coupled on its output and AC coupled input for the noninverted on the bottom.  

The output is a differential analog signal. But the input impedance is unbalanced and does not convert stray noise current or ground shift to a differential noise voltage such that the Common Mode noise cancels out.  

Maybe what you want for better immunity is a differential amplifier with precision matched resistor ratios or an Instrument Amp (INA).

Your suggestions won't work at all as others have explained.

The cct that works has an input impedance of 4.7k//{3.3k+Z(10uF)} 

There are other ways to do this but that was not your question.