BB:
I noticed you said "how the QS8s fill the back," which likely comes from car stereo installs. But Dolby Digital 5.1 surround speakers go to the SIDES of the listening area, well above ear level (2 to 5 feet, or more if you want) and slightly to the rear.
Now the QS8s are very adaptable and accommodatiing to asymmetrical placement, and they'll work well mounted on the rear wall, but that is not how 5.1 movies are mixed. And for music playback of older 2-channel stereo through 5.1 and DPLII, DTS, and Logic7, the surrounds work best to the sides of the listening area. Just wanted to alert you before you drill holes.
Regards,
