The Audio-GD products are completely balanced, so a balanced Amp/DAC means that it has a discrete DAC section for each half of the amp.
The 29 has very similar internal architecture as the 28, just without a balanced headphone out.
(edit) should add that all of AGD's amps use a current-based topology rather than a voltage based one. This is especially well suited for planars like LCD-X due to their impedance curve and basic operating principles.
Ah I see. Thanks for clearing the confusion.