I'm also a new owner of a Vive Pro. Got it a week ago.
I was disappointed of the poor sound quality from the headphones as you.
The first thing I did was to disable the headphones and use my older Astro A50 headphones that have a very good sound quality (not HiFi, but good for games and its wireless).
Today I started searching a bit deeper to find a possible solution. I come over this post:
https://www.reddit.com/r/Vive/comments/8fhjjs/my_solution_to_the_vive_pro_low_bass_issue/
It made the sound a lot better. But still not as good as the Astro A50 headphones. Maybe some tweeking in those setting may help you?
