Thank you for your advice.

I'll try to mount QS4 on the side wall and move the sofa 1- 1.5 feet away from the back wall of the family room.

Another question, does the speaker cables has to be same length for both Left and right QS4 ? I know it has to be on the front L & R but I don't know whether this matters for the surround. I intend to put my recevier on the side wall, so one QS4 has to be 10- 12 feet longer than the other one.

Thanks.