fyi, here is a portion of a followup response from T+A regarding AES48 compliance. I tried to parse the diagram in the draft AES doc but this is now officially way over my head :)
The analog signal circuitry of the DAC200 is referenced to the analog signal ground. This conforms to AES48 (see "REF" ground in figure_3 of draft AES48-20XX).
The generation of the balanced audio signal is already done in digital domain - not in analog domain. So this balanced signal is not generated relative to any (analog) ground.
[edit - another point of contention is that AES48 is concerned with the connectors, not the cable between them]