Audirvana Plus has a manual that goes through all the settings, and there's a forum on their website. The defaults take care of most of your critical options. If you're using it in iTunes Integrated mode, it works great. The only thing you have to "worry about" is SysOptimizer, which can shut down three activities; because I often work with my laptop while listening I do not have it turn off Spotlight indexing, and I found it can't turn off Time Machine (I filed a report on the forum about that). By the way, Audirvana Plus 2.0 is being developed and tested, but there's only one report of it being seen "in the wild."
Here are my settings, not necessarily in order. Three are not available while Audirvana is playing, but those are set for the defaults on my system. I have 16 GB of RAM available, and Audirvana wanted to take 13 GB, so I reduced it to 8, which ought to be plenty for the app and not impede work I do while listening.