In my opinion, the following are marketing gimmicks when they are present in a headphone amp:
Balanced I/O. Intended for microphone cables carrying extremely low-level signals, balanced I/O offers no benefit for line-level signals or headphone output where cable-induced noise is insignificant relative to source noise. It's just for show.
Hybrid operation. Adding a superfluous tube stage to a line-level signal path? At best there is no audible impact and the tube is just for show. At worst the circuit emphasizes tube colorations.
What is not a marketing gimmick? A Class A output stage. Class A operation greatly simplifies low distortion audio circuit design and power supply regulation, with real improvements in audio reproduction. The tradeoff is greater heat dissipation and idling power draw.
The beauty of headphones is that their low power requirements compared with passive speakers make Class A amplification (tube or transistor) possible in a small cost-effective design.
So how about a Massdrop designed Class A unit, without wasting money on balanced I/O or tubes? Maybe something along the lines of a discounted, customized Schiit Asgard 2?