@jreale you can try out the LUMIN app interface without having a LUMIN device, and as shown in this
photo the Tidal integration works the same way as playing music from your local music server.
The OPPO Sonica remains an incredible bargain considering everything you got at that price point, and it is unfortunate OPPO's personal audio business was discontinued. Which also means it won't get upgrades for direct integration with newer music services.
I think you should try and hear the D2's analog output for yourself because you may prefer the OPPO sound character. I do think the LUMIN app user experience is superior.