My new iPhone XS MAX have A12 engine , but DSP can not work , it’s made me crazy , what time Roon can supporting iPhone control DSP , because I use NAS as roon server , it is difficult to configuration DSP, I have no iPad my god , looking forward roon can launch iPhone DSP control version! Fast and fast and fast , it is a very important function for real music player !
The DSP runs on the Core (the NAS in your case). It doesn’t matter how powerful your client (iPhone) is. Not sure if or not your NAS is powerful enough to support DSP.
The iPhone Roon client allows you to turn parts of the DSP on/off, but not configure it, e,g., define EQ curves. I think this has to do with small screen size and not how powerful the hardware is. You can always use a Windows or Mac laptop to fully configure DSP.