Ok, update. We learned something. The clean install of Win 10 initially had the same problem - the speakers were recognised, but not the headphones. plugging them in would do nothing. However, windows found and installed “Realtek audio control” automatically and things started working normally. my guess is the linux driver is just out of date now. I am going to have to wait until the ALSA guys get that sorted out, as the realtek drivers are for kernel 3.18 or something, years behind 