Every 1 of these options requires a computer. How are you going to rip music to a NAS drive? Also, how are you going to backup the NAS drive or any drive you use? If you go with any of these servers listed above with internal disks, you have to ask the questions since nobody lists these:
How do you backup the data
How do you increase disk capacity
If you buy 1 of these servers above that has a dac inside, how do you update the dac with new features that will be coming out? Dsd2 for example.
Because of all this, and with the quality of the output, I use a dedicated Mac mini with audirvana plus with multiple multi TB FireWire disks so there is fault tolerance with an external DAC all controlled thru ipad