Why is QuickTime’s volume significantly softer than VLC’s?

Why is QuickTime’s volume significantly softer than VLC’s?

I have a Unibody Macbook running 10.5.5. When I play videos in QuickTime the audio is low even after I raise both the QuickTime volume meter and the system volume meter to the maximum. When I play the same videos in VLC, the VLC volume meter allows me to raise it to a louder level.