yes, this simple design is using LINEOUT analog outputs, so your Volumio build will work without any additional change. The left 3.5mm jack is corrected to LINEOUT pins through DC-blocking capacitors, the right one is connected to a headphone amplifier (inputs for the amplifier are the LINEOUT signals as well). I already ordered some bare PCBs from China, they should arrive in NL within 3 weeks.
I am confident this design, together with a RockPi-S, will be a very good and cheap setup to run Volumio, because the quality of the embedded DAC is more than acceptable.
I made this simple design to have a good starting point for other projects, creating some variants with I2S DAC/AMP will be pretty straight forward.