Thanks Pipeline. It's weird that I never had this problem before, I always had asio selected, but I noticed that since I installed 2017 youtube sound was also effected, if I had RB running, then no youtube sound.
The problem seems to be only in RB as BiaB works fine with asio and realtrack preview and youtube.

I couldn't find the switch for "asio always on" in Realband, but found it in BiaB under Audio Driver Settings.
After de-selecting it, everything worked. Asio is selcted in BiaB, RB, and previews are ok, and youtube works ok.
grin

Chris