I was using VOX previously -- but the tiny UI was such a drag that I couldn't take it anymore. Then I moved to Fidelia, which was slightly better, but the way to view and search your library is completely barbaric!
http://www.audiofile-engineering.com/fidelia/
In addition to Destroyer, I use Audio Hijack. It lets me do custom audio routing, DAC managment, adding Audio Unit effects, equalizers, etc.
Love the Concero, I would recommend it. I believe it has the same chip as the Invicta, but you are spending less than $1k vs $4k. Its really small, USB powered, and sounds great.
I REALLY like Fidelia's UI, but it is such a subjective thing, some people might hate it. The FHX processor feature is great as well. It has a free 15 day trial, so I would recommend just giving it a shot. If you like it great! If not, you just go back to Itunes after 15 days having lost nothing. It is worth a trial at least. My friend just switched to it after my recommendation and he swears he won't be going back to Itunes ever again. http://www.audiofile-engineering.com/fidelia/