I'll post this in a seperate post:
I've gone back to the "non beta" drivers from March (2016) and they are loading perfectly - every single time.
I've been having problems with the beta drivers - where sometimes, there is no audio interface for SONAR (or any other Windows apps) to use. It's gotten a little worse with each beta version - and I'd have to power cycle the Ultralite AVB and/or the PC and/or mess with buffer settings (and then put them back where I want them) - to get the driver to load - so SONAR etc can see the interface.
Once loaded - the drivers work great - it's just a problem actually loading the driver. (especially after a reboot)
Just to check my sanity, I went back to the non-beta driver and it works perfectly.
Win 10 64 bit, Asus P8Z77-V using a (onboard) Intel USB3 port with no other devices sharing.