AirPlayXPCHelper

AirPlayXPCHelper is a macOS background process, at /usr/libexec/AirPlayXPCHelper, that runs as root and handles AirPlay output. It reads audioLatencyMs from root's preferences and builds its audio engine once per process, so a new value needs a restart, which drops the current AirPlay route.

Related: audioLatencyMs · audioLatencyMs explained · Source: Preroll notes