Unbalanced signal into a balanced input... sure. I would not disagree. The typical 6dB per octave rising CMRR curve would seem to add that coloration directly to such a signal. Sure, the mode converted signal is at a lower level, but it's far from flat, so it has the potential to make a difference. It's all perfect in theory yet none of our devices work that waySo, according to that, any unbalanced stage is asking for trouble?