Longstory story: computeraudiophile.com for the most expertise,
Users report success and frustration with Audirvana+, Amarra, Pure Music and JRiver for a variety of reasons. Jitterbugs and Uptone Regen and a million different cables have been beneficial too.
Narrowed down to tweetable reply:
A+ and Jitterbug and you're probably there...
Cheers,
Spencer