I was thinking of getting a low power machine to act as a dedicated Roon server and stream to a Raspberry Pi/DAC, like the Quad Core Cubox i4x4. Is this an acceptable platform its a ARM A7. In fact with the Cubox optical out I could get a DAC and dispense with the PI altogether.
In the end I decided to just pension off my watt guzzling ancient PC, remove the QNAP NAS and a bunch of other services always on and run a modest 2-disk RAID off the Raspberry Pi Roon EndPoint and get a more power-efficient modern Mac. Maybe not the best Watt/h solution than a Nuc, but pretty close.