You can get 1" thin absorbers to knock down the midrange echo. You can get fabric covering on them to match almost any paint color. Music, conversation, even billiard breaks will sound better.
Normally, the panels between speakers and on side walls (and ceiling) absorb the first reflections of sound from the speakers that would do the most damage to the spatial imaging illusion when listening in the sweet spot. If thick enough, they can also be potent bass controllers because they are very close to the speakers. But since your pool table is in the sweet spot, and you will not be doing super critical listening down there then the panels in those locations only serve to reduce room echo in general.
A friend of mine has a pool table in his basement, with all concrete walls and floor. The echo is so bad it is hard to have a conversation, much less yuk it up with beers and pool. I told him about acoustic treatment, he looked at me like I was from Mars.