> My audio interface for connecting my keyboard/guitar to my PC is USB-C. I tried USB2 devices and find they have too much latency. It's very noticeable. USB-C has 1ms latency or less.

Are you sure that's not just USB 2.0 interface being shit ? USB2.0 is certainly fast enough to have sub-ms latency.

I actually wondered about how to go with testing USB interface latency, maybe I should test mine when I have slow weekend...