I have a RPI3 with RPI 7" display and HifiBerry Digi+ hat going into a TEAC UD-301 DAC and it’s been running fine using Core to upsample to 176/192. I’ve been testing it today using Core to upsample to the TEAC’s limit - DSD128 (5.6mkz) and it seems to be running ok.
I know the RoPieee doc says use a RPI4 for USB but they’re still pricey and hard to get so I was curious about how stressed the RPI3 is which is why I am asking about SSH access.
As to the recommendation to use a Pi4 for USB (all things being equal), this is only because of the shared bus with ethernet on the Pi3 (as I recall) – otherwise it will work fine.