Sunken Harp = Big Tone

Hold your harmonica with both hands, using your standard cup. Now look at your harmonica and note how much of it is in your hands. The more of the harmonica in your hands, the less you can place in your mouth. The more harmonica you can place in your mouth, the larger your embouchure is (the harmonica acts like a wedge... opening your mouth the deeper it's wedged in). The larger your embouchure, the bigger your tone.