Purely sonically, transformer coupled output has more calm presentation, with more quiet background, and somewhat more precise soundstage. On the other hand, transformers can lack some definition at the most bottom end. Actual benefits and shortcomings will also depend on the environment.
Two new articles bring more details about the ultimate volume control used in the Model A. The first article describes the approach, and the second one brings more information about cermet potentiometers.
Check them out.
Asynchronous USB Audio Class 2.0, galvanic isolation, two oscillators, and reclocked simultaneous data output. With U.FL output connectors it would be adequate companion to AYA II 2014 or DS board, and of course the great possibility to connect PC to Model S MkIII, and use TDA1541A in simultaneous data mode. It will also support balanced topology.
Premium version of Model A uses Audial made, real copper binding posts. Now these are available for separate purchase.
Even though it was discontinued in 2009, the interest in this great DAC never actually disappeared, so it had several after-runs. “DS” was its 2015 release.