For Sonar 8, WIN10 with a Terratec DMC6Fire USB and audio engine drop outs:
 
The driver to look for is by google this: TERRATEC UPDATE 10546-10-64
 
To avoid audio drop out:
 
Options-Audio - "Sample rate" = 44100
 
Advanced Tab - Uncheck "Share Drivers with other programs"
 
Set your computers Speaker Properties in Advanced tab to 24 bit 44100
 
Problem solved!