Hello junh87.
The good points
As one of the largest instruments in the orchestra, it is probably not possible to capture the whole body in the way you want to shoot it. What you have shown - the neck, head and scroll of the double bass is classic and in my opinion, has already delivered a message related to the instrument.
I like the way you have positioned the neck of the bass, a little slanted, the way it should be held. And your low-key approach means that as a viewer, I would only need to direct my attention to two parts - the player's face and the neck board of the string.
The slightly less good points
It's about exposure. In order for my attention to be drawn to the face and the strings, do give these two elements a bit of a dodge in photoshop, or increase the exposure slightly - perhaps by another 1 stop. I think that will make it just nice.
You could possibly darken the out-of-focussed flutes in the foreground with bit of burning in photoshop so that they would be less of a distraction.
These are but my humble opinion.
Otherwise I must say I quite like the feel of this low-key shot in monochrome.
Thank you for sharing.