There are a couple of threads at erji forum which did pretty comprehensive comparisons between all or most of the amp cards:
Here are some comments about all the official hifiman amp cards by Dr Fang himself:
They are all in Chinese. Maybe google translator can give you some answers.
Kinda forward for me to ask but is it possible for someone here who understands Chinese translate that, maybe not word for word but at least the important highlights please? I think that'll be a much more accurate translation than Google translator I'm sure.