I have upgraded (an XPS L702X) yesterday night and I now have the same problem. Have you found a solution?
In my case, it has happened so far only when resuming from hibernation or suspend, not on a clean system start (I haven't tried that yet).
I figured out a solution.
1: Remove all sound drivers in Control Panel - Device Manager
2: Instal Realtek Audio Manager
3: Restart, then reinstall audio drivers if not done automatically.
Thank you, I take note of this for later as I have decided to downgrade the laptop back to Windows 8.1: several of my daily tasks can no longer be performed and the system is so much slower.