EDIT: forgot to say it work from 10 - 99 %

hi ,
like to share my solution ( i use alsamixer to set volume) :
virtual switch with slider (in my system : id=71)
on action run the script set_volume.sh:

pi@tana-rpi1:~/domoticz/scripts $ cat set_volume.sh

v=$(curl -s "http://192.168.10.181:8888 ...