I enchanted my bow with power and it gave me Posture Breaker with it. This wouldn't be an issue if it didn't play a sound that's way louder than every other sound in the game every time I shoot a mob.

I could lower the game volume but then everything is quiet. And because enchanting tables are random I have to waste XP to get a bow without this enchantment.

What version is this? The bow shouldn't be able to get Posture Breaker in the newest, which is the optimal one and where the sound should have been lowered. Consider updating if you're not using the newest 1.0.2 version.