Great, so.... The Aries Mini sits between the router and the ND5XS. Am I now using the Aries to access Tidal and Radio, or the ND5XS still?
You would use the Aries Mini. In this setup, the ND5XS would act as a passive DAC, fed by the SPDIF output of the Aries. Please, keep in mind that you would not be able to use the Naim app to control the Aries. You would have to use a UPnP control point to control the Aries and the Naim app to control the ND5XS. Of course, you could also disconnect the ND5XS from you network and just use the Aries to send both Tidal and local streams to the DAC section of the ND5XS. I have never used an Aries Mini or a ND5XS. Thus, take my remarks with a grain of salt. Best, nbpf