the QNAP TVS-x71 are awesome in the i3 or i5 (i7 is too hot and the non-coreiX sucks)
I am experimenting with a new configuration of them that seems pretty sweet… the TVS-471 has 4 bays, which I suggest you configure:
1 bay with a small SSD (120GB, about $40 right now) for the Roon Server install + database
2 bays with 6tb drives RAID mirrored
1 bay with 6tb drive for weekly backup off the mirrored set
the SSD gives you get fast performance for Roon (I would never run Roon’s database on a spinning disk)
the 2 6tb mirrored drives gives you 6tb of fault tolerant storage for music (about 15k cd quality albums)
the last 6tb drive gives you a weekly or biweekly local backup of your music (remember, RAID is fault tolerance, and not backup)
We’ve not made the QNAP package for running the Core, but the TVS-x71 series is the QNAP to do that with, once that package is available.
The whole thing is under $2k and pretty awesome to stuff in a closet or rack away from your listening room.