Title says it all. Im a bit confused. Can I play FLAC files on my SSD/harddrive on my Mac Mini via Roon?
Ask a simple question, get a simple answer: Yes.
(I just tried this on my Mac Mini here to confirm, seems to work)
Thanks for the fast response 
I wasnt sure if Roon would play FLAC files on Apple’s OS or I needed to buy ALAC files instead when I buy music.
You’re welcome 
One of our more important design/UX principles is that everything work everywhere. So if we support a format at all we need to be able to support it everywhere.
Not being able to play FLAC on Mac is an iTunes issue, but not a Roon issue. However, the FLAC issue in iTunes will be resolved in the next OS.