MacBook Pro is a great choice. I find Linn Kinsky/Minimserver/BubbleUPnP combination to be killer good, much better than Roon. You will need a renderer like Sonos or Interchange to use with it to go from Ethernet to S/PDIF coax. Much more costly than $1K, more like $4K.
I would deter you from buying cheap throw-away toys that deliver mediocre SQ.
I can recommend the following combination for around $2K that will outperform 99% of servers and will play local files on any computer that on your LAN and will stream most services. This is truly a reference level sound for not much money:
AQVOX AQ switch V1 ->
0.5m Ethernet cable ->
EMO EN-70e isolator ->
2.0m Ethernet cable ->
Sonos Connect ->
Markertek Coax cable ->
Synchro-Mesh/OTL reclocker ->
Empirical Audio Standard 4 foot BNC coax cable ->
Your DAC
The total for everything, less the Ethernet cables is: $2198
This setup will upsample the low-res streams to 24/96 to sound best on your DAC. Jitter is 7psec, lower than any server on the market:
https://www.audiocircle.com/index.php?topic=157348.0
Sonos software is really easy to use and is rock solid.
If you want to upgrade to a better renderer than the Sonos Connect in the future, you can re-use everything except the Sonos. The Synchro-Mesh can be used for reducing jitter from a transport, Smart TV or an Apple-TV etc. The Synchro-Mesh has a second Toslink input you can select from these other devices. Makes movies much more enjoyable.
Steve N.
Empirical Audio