I’m thinking of switching from a single unit acting as core and endpoint, to separating the core and endpoint by adding something like an SOTM. Currently I have a linear PSU for the single audio PC. My question is, if I switch to a 2-unit setup, presumably the endpoint should be fed with linear PSU, but does it make a difference for the core (which is now separated from the endpoint by Ethernet)?
In my experience, a better power supply always has a positive effect on the sound, and you will still have enough power. In addition, most switching power supplies have negative effects on the entire power supply system, as has often been described. I therefore use a linear power supply wherever possible and affordable.
The endpoint should be fed with a high quality, low noise, fast transient response, high bandwith psu, be it either linear or smps. The term linear alone says absolutely nothing at all about the actual quality of the psu.
But my question was - how important is the power supply to the core, when the endpoint has a high quality PSU and the core and endpoint are separated by an ethernet cable.
Not so important, it all depends on your groundig scheme. If you don’t have any groundleaks/loops you will not likely here any difference.
I would suggest you try it if possible. If it isn’t apparent to you then sell it on or repurpose it. (You’ll keep it!)