PC World has an article on why USB-C has not been a viable alternative for the 3.5mm audio jack [pcworld.com]. Problems with USB-C include variable handling of digital to audio conversion, incompatible SOCs inside the cable, and non-standard analog-passthrough. In short, the cables which contain computers themselves are not standardized in behavior and his conclusion is that mobile devices must have 3.5mm jacks until the USB-C cable technology get sorted out enough that they become usable.