Mark, if you wanted a cheaper point of entry just to check things out, a raspberry pi or Cubox are good starting blocks - many of us have started using the super-slimmed down Dietpi OS. It’s free and pretty easy to install (super easy for RoonBridge on the pi now). I believe the HQPlayer NAA is on the verge of being added (if it’s not already). See this topic DietPi: creating a lean-and-mean Roon Bridge
The sonicorbiter is a stock Cubox, but with a custom OS. If you don’t need the os and are happy to install something like Dietpi then you can get a really affordable network>USB box. The pi is more limited for high sample rates because of the shared network/USB bus - but personally I’ve never had an issue with mine in terms of high-res files (I don’t use HQPlayer NAA, just RoonBridge).
[just looked up the oppo and seems it’s max sample rate is 192 so the pi would probably do, and if you upgrade later, you can use it in another room. Also just realised Dietpi isn’t on Cubox yet, but is on their radar. Odroid might be worth looking at too]