No,I don't restar my mac.Never heard that this can be important
I think only need to restart if your dac does not get recognized and assigned to the software player although I read somewhere that if you switch between Amarra and Audirvana it is recommended to restart. I like Amarra SQ so much more than Audirvana that I don't use Audirvana any longer.
However, I will certainly try Vox after what you reported (also thanks for posting your hardware details).