When I open mp3 in Rhytmbox by double clicking on file in Nautilus than it seems to work OK = no auto decreasing in volume level, but if I start Rhytmbox from desktop (.desktop file launcher) or by shortcut key and than start playing mp3s from playlist volume level get automaticaly decreased from 100% to 0%.
One more think I discovered:
When I open mp3 in Rhytmbox by double clicking on file in Nautilus than it seems to work OK = no auto decreasing in volume level, but if I start Rhytmbox from desktop (.desktop file launcher) or by shortcut key and than start playing mp3s from playlist volume level get automaticaly decreased from 100% to 0%.