Please do yourself a favour by running the Amarra in the independent mode (without iTunes) and add tracks to the Amarra playlist and play solely via Amarra itself.
The sound far bests any other players I have - I have Audirvana Plus, Fidelia and Decibel and they cannot come close to the Amarra SQ when songs are played via the Amarra playlist.
When songs are played on Amarra with iTunes integration, the SQ takes a deep plunge.
With iTunes integration, I find Audirvana Plus to be better than Amarra but no way close to when Amarra is running independently.
A downside to the Amarra playlist is that it is still very clunky and slow. Lack of library management is a big minus as well. But they can be forgiven when music starts playing =)