Play audio from command-line/non-volumio process

Good evening!

Hope the title will be comprehensible for someone :smiley: I’ve had a hard time deciding

I’m brand new to Volumio, but see quite a lot of potential here ! Running it on a Raspberry Pi 3 with JustBoom DAC. Installation went well, first test on playing WebRadios and Spotify are OK.

My project is to port a app I developped on Raspbian before, mainly consisting on python wrapping around fluidsynth MIDI synthesizer and sending sound through alsa driver.
Installing requirements in Volumio seems OK. The issue is no sound outputs to DAC. The program however seems not to notice any problem.
Going even one level simpler, logged via ssh I can’t even play audio file using sox/play, so there is something I must be missing concerning the volumio expected usage.

Any suggestions? Please ask if more information on my procedure or anything is needed for comprehension. Thanks!