Why use a dedicated server? First, you have to ask yourself, why use usb input on the dac?
Once you decide to use a network interface and not usb, then your requirements change. If you use a network interface on the dac, then you can use a OS X or Linux server to run Roon or Audirvana. Never use a server in your audio room. If you decide to use usb, then you should use a music server that has the best usb link, then you have to buy other accessories to help usb sound decent. Years ago I demoed many music servers and found the Auralic Aries the best, over Lumin and Aurender, and their DS Lightning software was in a different league over its competitors. If you want to go cheaper, then find a Aries mini, much better than the bluesound.
Once you decide to use a network interface and not usb, then your requirements change. If you use a network interface on the dac, then you can use a OS X or Linux server to run Roon or Audirvana. Never use a server in your audio room. If you decide to use usb, then you should use a music server that has the best usb link, then you have to buy other accessories to help usb sound decent. Years ago I demoed many music servers and found the Auralic Aries the best, over Lumin and Aurender, and their DS Lightning software was in a different league over its competitors. If you want to go cheaper, then find a Aries mini, much better than the bluesound.