MOTU 896 MK3 Windows 10 dropouts

I had my system working fine with Windows Vista (quad core pentium, 6gb ram, Sonar X1 Producer, ASIO drivers) running MOTU 896 MK3 FW with an MUADIO 8 channel mic pre connected via ADAT lightpipe.  After upgrading to windows 10 I am experiencing dropouts during playback.
 
For a test I try to play the the Sonar tutorial AUDIODEMO.CWP and it (usually) plays fine.  However, there is another sample project that is full of midi sequences and keyboard parts that I can't play at all without dropping out, stuttering and skipping.  I also recorded 8 channel audio (8 drum mics) and tried to play it back and I also get a bunch of stutters, skips etc., though they occur at different parts of the track, so I'm assuming the problem is with the playback and not the recording.
 
I've gone through every "optimizing windows 10" type thing I can find and nothing seems to fix it.  I've changed every recommended parameter that seems to affect playback and still nothing.  I've also re-installed the latest MOTU driver using their Audio Installer that says it will install the latest driver.  (I also find a thread on how to removed old versions of the driver that may be lurking.) No luck.
 
Going by everything I've read, it seems Windows 10 should offer good performance for Digital Audio, but I can't get this system to work right.  Again, this exact setup worked flawlessly before under Vista.  The only change is the OS (windows 10) and the new drivers for the MOTU.
 
Anyone have any ideas on what I can check?
 
Thanks!
 
Tom