There seems to be a problem with the WAS Driver after loading the Build #512 Update. WAS driver was working OK with prior Build #508 though! After I loaded #512, I measured that it took around 30 seconds to hear any sound after the note was played. This is on Windows 10, Build 1709 (Fall Creator). I'm using the internal Realtek sound system. Switched to MME Driver, no problem (other than the usual millisecond latency associated with MME). Also tried the ASIOFORALL Driver, and that is working OK as well.

Guess I'll sent an email to PG Tech Support. I'd call them, but I've had no lucking getting thru on the phone to a real live person for the last month or two.