Spoke to someone from Axiom today regarding trading my QS8’s for M3 in walls to get 5.1.4 going. She said there was no need...to keep my QS8’s and that they would work just as well as direct firing rears.
I did end up getting four M3’s for my heights. But I’m concerned about the rears. It goes against what Dolby says regarding proper speakers for Atmos.
Will using the QS8’s be a less optimal setup?
Also my back wall is maybe four feet from the listening area. Is that too close to put the QS8’s at ear level?
Will they work? Sure, but you're correct about Dolby guidelines. Using QS8's won't allow for sound 'objects' to be placed as accurately in the room, as the QS8's will fire sound in 4 different directions.
https://www.soundandvision.com/content/can-i-use-dipole-speakers-714-atmos-setupIf you're going through the trouble and expense of going 5.1.4, you're probably best to follow the guidelines as closely as possible. Having the rears 4ft behind is a bit on the close side, but shouldn't be an issue. For Atmos, you'd want them to be at about the same height as the rest of your listener-level speaker, but you can go up to 1.25x the height of your fronts.
Full disclosure, I've never heard QS8's, but I did just put in a full 7.1.4 setup (entirely in-wall, minus the center channel and subs).
And finally, if you're really agonizing over this, Axiom is incredibly flexible in terms of letting you demo their stuff. You could order the M3 rears, and test them out against the QS8's.
