Unfortunately I've tried the fix above to disable asio drivers, so as prevent GX components from loading with windows but it didn't fix the problem (so as disabling pci-e link energy management). On my offending system, other than the usual loss of the right channel that was fixable with a driver restart, the banshee scream only started on a very regular basis (maybe >6 times a week, sometimes twice a day, with some odd 2 week intervals) after 5 years when I moved to W10. Before it did happen probably once under W7 or W8.1, can't remember.
Since then, I had to replace that Asus DX (sorry, not a relevant STX, but suffers the same) with an OEM SB Z for 2 channel analog output. That one, on the other hand, seems to suffer ocasional pops even when not playing anything, but what's curious about that, is that it happens to be an HD Audio compatible device and the same happens with an onboard realtek on another system.
Now that W10 RS1 is out, has there been any change for other users? Only mindbomb seems to have reported an improvement. If I find the courage to put it to use again in another W10 RS1 system I'll report back.
Edit: Sorry, wrong user name.