When players fear making a mistake they play softer as they fear embarrassment. Now that you can see the music a bit better I'll bet you play a bit louder. There is an old Indian company that builds instruments that sort of brags on how lightly their instruments play. The brass feels dead when you play it but the pitch and intonation aren't bad. But you blow forte and the horn plays pianissimo no matter what you do. The instruments are inexpensive and hard to dent as the alloy and the thickness of the material is all wrong.