Just recently started using Volumio with a Raspberry Pi B+ and HifiBerry Digi+ board into a DDDAC. Really impressed with the sound so far but will soon be trying I2S out directly to my DAC.
Keep us posted how you get on. Can chat more end of jan.
I’ve tried ps audio and project dacs on i2s but have come across manufacturer comms issues (well that’s my assumption).
E.g. How easy is it to create a Volumio driver ?