If you can’t wait for the Volumio image for your Pi-3 you can use Moode instead (moodeaudio.org). You need to be able to add some files from Raspbian, but if you can you build a Pi-3 compatible image. See diyaudio.com/forums/pc-based … i-198.html post 1975 and post 1998 for the internal WLAN.
I did it and can play audio through my USB-DAC. I don’t have a I2S dac so I cannot test it in that configuration, but I assume that it will work also.
I use the internal WLAN now and best thing is that I don’t hear the soft clicks in the playback via my USB-DAC anymore !! 
(See my post regarding my Audio-Gd NFB 11.32 USB-DAC)