It is perfectly normal to experience differences in volume between different sources. In fact, there can be differences in volume just by changing the channel on the television, switching to a different cd, or changing the game that you are playing. There is also no need to worry about turning you receiver to any numeric level on the display. The only thing I would be sure to do in a case where the sound is very quiet unless turned up substantially, is to be sure to turn it back down before changing to a different source that may be louder.