[solved] sound on audio jack instead of hdmi

[mclien]

Hardware
Device type and model: raspberyPi 4B, 1,5GHz 4GB
Power supply rating: 5V, 3A (USB-c)
SD card size and make/type: 32Gb, class10, HC
Network (Ethernet or wireless): Ethernet
Connected devices (TV, USB, network storage, ...): Beamer HD (hdmi), nfs-share

Log files
Link to logfile(s): let me know which one from /var/log will help wit the problem

Problem description:
All I want is getting the sound output from the headphone jack instead of the hdmi.

But all howtos are about getting it work with hdmi, which it does our of the box. Therefore I couldn't find any entry which would bind it to the head-jack (bmc2835). At least I couldn't find the corresponding entry for the /boot/config.txt

What I do have:
-the sound module bcm2835 is present in lsmod
-the kodi audio setting has only hdmi outputs select-able.
-the hdmi sound works (beamer has a lousy mini-mono speaker)
-using the hdmi output form the beamer works (so the silly hardware solution would be to have the hdmi cable upt to the beamer at the ceilling and than an extra audio cable back down to the raspi)

Sorry if I was just again to search with the right keywords.

Software
XBian version: 20231207
XBMC/Kodi version: whatever come with the above
Overclock settings: none

How to reproduce:
Install the above image on the above mentioned hardware and try to get a headphone plugged into the raspi head jack work.[/term]

EDIT: Or do I need to install alsa utils first to get it working at all?