[PROBLEM] Moode 6.5.2 and old RPI2

[mancio61]

Last night I try to connect the old RPi (with no DAC HAT for now) using another Wi-Fi dongle and works perfectly. In the meantime I connect it to the AVR through HDMI, but if I'd want to connect to the 2ch Stereo Amplifier, I suppose I have to use the 3.5" audio jack of the RPi (supposing I have to use a 3.5" jack <-> RCA Stereo cable). Do I need some configuration to redirect audio stream through it instead of HDMI or is it automatic ?
thanks