Congratulations. Primo looks totally primo! I am running Volumion on a 1st gen Tinker Board, so I think you have chosen an SBC that is better than the Pi for this application. I just spent $3,500 yesterday on a vacation in Mexico, or I would order one right now. Will the internal DAC do DSD?
you may interested in the power consumption of volumio primo (9028QM board with Tinker Board S.
it’s approx 3,25W .
Thank you very much! Glad that you understand our choice to go with Tinkerboar S.
Primo does DoP 
The specs and reviews look great so far. Congrats! I like the direction that Volumio is taking towards the mainstream market (vs. serving solely the DIY niche). I wish PRIMO will come to the U.S. soon.
My wish is that Volumio will make a balanced output version in the future (similar to the path that HiFiBerry went down to make DAC+ Pro XLR). It will also be great to have the option to play PCM files as DSD via DoP (similar to Terra-Berry DAC2). I like both of these features on the two DACs. If Primo offers options like these in the future, it will be potentially more disruptive to the higher end market.