Formal dress for the dumpling dinner in X'ian

I think the nice black top with black suit pants and high feels are formal enough for the dumpling dinner and the show.
The dressing depends on what kind of situation are you going to attend. If you accopamy with your friends to the dumpling dinner and the show, you can wear whatever you like. There is not a certain regulation for the dressing.
If you are with your parterners or clients, you need to be formal.