I have been mulling over this tweak with a friend of mine, but I think we need the input of the head guru Nicholas.
Basically, the question is: what happens if you use a cable that converts xlr to rca? I think this cable would ignore the ground output of the xlr, send + to + and - to the combined -/ground part of the rca plug.
The configuration where this would be used is as follows. The DAC has xlr outputs which are, as far as we know, fully balanced (i.e. differential). These outputs go to the TVC ref4, which has both xlr and rca inputs and outputs. From the TVC to the amp, unfortunately, there is no xlr option.
So far I have been using the rca outputs of the tvc to the amp, and things sound fine. But... would I get an extra 6 db of gain by doing that cable conversion, and going from the tvc's xlr outputs instead of its rca outputs?
There is another question: does the quality of the signal improve by using such a cable? It would seem that the TVC really, really wants to use the xlr outputs (it is a differential circuit by nature) and the rca output represents some kind of compromise, since the - and ground outputs of the xlr are mashed together into a single wire for the rca outputs.
If it matters, the amp and the dac use 2-prong power cords (no third prong that goes to ground), so I am a little fuzzy on how the xlr 3-prong connection can fully work its charm.