I currently own Audirvana+ 2.6.6 but am curious about version 3. I would really like to install the 3 trial but am afraid of it messing up my current library and playlists in case I decide to stay with 2.6.6 and not to purchase the 3 upgrade.
I would appreciate any helpful advice.
They both share the same library, so download trial version of A+… good for free 15 days.
Before you use it, rename your 2.6.6 Audirvana application to ‘‘Audirvana Plus 2’’ so it will have a different name from the trial v3 version that you will pull in the applications folder… so you’ll have two A+ in your applications folder.
Then to be sure to keep your 2.6.6 preferences and music database, copy to 2 files before opening the v3 version:
Go to User… Home Folder… Library… Applications Support… Audirvana Folder…
COPY (with alt key dragging that file anywhere else out of that folder for you to keep)
the AudirvanaPlusDatabase.sqlite (that is your database of music).
Go to User… Home Folder… Library… Preferences…
COPY (with alt key dragging that file anywhere else out of that folder for you to keep)
com.audirvana.Audirvana-Plus.plist (those are A+ software preferences)
Then open the new v3 trial application and everything should be normal except the new sound different from the v2 version…
you like it or not, or with MQA or not 
IF you want to reverse to 2.6.6 version after, replace the 2 files that you saved in the same position folder and trash the v3 trial application… and renamed back the v2 app to its original name ‘‘Audirvana Plus’’ and you are back where you were… but i think, you won’t reverse back