Hey Sirclyde
We almost have the same size room. My room size is 11x19. At the beginning of my setup, I could not decide if I should have a 5.1 or 7.1. I didn't know if 7.1 was going to be to much for that size room. I wounded up doing a 5.1 BUT, wired the room for 5.1, 6.1 and 7.1. Guess what????? Now I want to add more speakers. I am going to try the 6.1. I am going to add a QS8 in the back center. The reason that I am going this route is because of what SIRQUAK mentioned at the beginning of this post, "The QS4's and QS8's on the sides will make you think that you have a 7.1". So that means that I do not need to add two more speakers on the back walls (saves me money). As I do get that 7.1 effect now with 5.1 , I think that by adding another QS8 in the back center, It will give me more of a real surround effect. Just my opinion.
