Im not sure if a different server will make a significant difference in sound quality but if you have a "larger" music collection you might want to give Andrew Gillis at Small Green Computer and look at one the i5, i7, or i9 servers. Also consider watching a few of Andrew's video or better yet email / call him about cabling and the use of fiber. The X1 is a good piece of equipment. I would see how he suggests leveraging its capabilities.
I'm not associated with SGC just very happy with their customer support and equipment.