I recently bought the HiFime Sabre 9018 USB TYPE C
and can report that it works with the Lumia 950 and it shows up as an external monitor. The sound is more open and each instrument is more clearly audible.
There is however one major problem, and that is the connection between the DAC and the phone. When you have the phone in your pocket, the USB plug will disconnect because of movement, and that will result in the music stopping or juttering, and often you will have to reseat the plug to get the music going again.
So to fix this problem I've made an attachment to the plug that stabilize it, which makes the DAC usable again. It is not pretty, but it works. The angle between the plug and the wood works as a clasp that hold the plug tight in the phone. (Actually I had to attach another piece of wood to tighten the grip on the phone). If somebody had a 3D printer they could probably do a more elegant job than mine. :)