With admittedly less than ideal surround placement like this, it sure is a good thing receivers let you calibrate the speakers. Make sure you don't overlook that critical step. It will boost the signal to the furthest QS8 so it sounds just as loud as the other one -- and all the other speakers, for that matter. With calibration, I'm sure it will sound just fine.
I can explain it to you but I can't understand it for you.