Thanks! I also used winsound on Windows, packing it into a class that mimics psychopy.sound.Sound. See https://github.com/lindeloev/psychopy-course/blob/master/ppc.py. It plays with around 2ms latency on the systems I’ve checked but on one other system, it did terribly (30 ms latency and then 20 ms jitter on top of that).
It’s clever that you load the file beforehand. I should do that as well.
I’m told that the timing is bad on Windows 10, but I haven’t tested it myself. Apparently, Windows 10 choose not to have a super-low-latency no-equalizer audio backend for system sound 