What is your goal? More bass? 4 Speakers rather than just,2 ?
My room is bigger than yours and I have faced the same issues. I also listen mostly to classic rock and blues. And I have struggled with upper midrange glare.
My system was improved greatly by 2 subs. Now it sounds very good. I agree with @noromance concerning the pair of Rel subs. But I would go with the S series with a 12 inch woofer which is what I have..