Volume from shairport-sync to Airplay and back

When I switch from shairport-sync to Airplay and back to shairport-sync, the volume is set to 30 percent, approximately. It’s great and I avoid too much volume by accident. But it’s just still too loud for my system.
Anyone who can help change that? My system is: RPi> usb dac> amp and no volume control in Volumio

I have looked at shairport-sync.conf to see if I see a code there that puts volume when connected to the device. But I did not get wiser.