First of all thanks for taking the time to make a drawing Eduardo. It makes it so much easier to understand what you are dealing with.

Based on the dimensions of your room and your seating layout I would go with wide speakers. Your room is wide enough compared to it’s length I think the wides would really help to extend the front soundstage and make it more immersive, especially for the side couches. I would put the wides as far to each side as you can. And bring them out as close to the seating as you can get them without them sounding to close to someone sitting in the front of the nearest couch. I would angle them so they are not quite pointing straight to the back of the room but rather at the nearest side of the couch in the back of your room. That should help form a better soundstage while still leaving the nearest couches in the speakers dispersion pattern.

If possible I would also move the side M3s back a little bit so they are just behind the last seats and angled in toward the center of the group of seats. This will help make up for the loss of the rear speakers by creating a phantom rear effect in stereo between them. You could simulate this just by moving your seating forward temporarily if you have the room. That way you can get an idea of how it will sound w/o moving the speakers if they are wall mounted.

You may not want to hear this but it’s going to be the best advice I can offer for your situation. If you can afford to get a pair of QS speakers even if it means using Axiom’s trade-up program to trade in a pair of the M3s you will gain more improvement than any other single purchase IMO.

http://www.axiomaudio.com/tradeup.html

Trading up your side surround M3s for a pair of QS designs will give you a noticeable improvement in surround sound for all your seats. Their dispersion pattern would cover all of your viewing area much better than a direct radiating speaker and IMO be well worth the investment.

Finally, I think it’s a coin toss as to height or rear speakers working better in your situation. Your room is wide enough to mount them on the front wall so the M3s should work ok but your ceiling height will limit how much ambient effect you get from them. If your room is normally full with people sitting on the side couches then height speakers would benefit those seats more than rears by spreading more sound around the room especially for scenes with wind, rain and echoes. However, if most of the time you only have people sitting in the back couch then rear speakers might benefit you more since they will help fill in the back soundstage for those seats. OTOH, if your side surrounds were QS design then I think they would spread the sound around enough in the back to make heights a better choice.

I know I must sound like a broken record but there is just no getting around the fact that the QS design does a fantastic job. For 3 years I ran only a 5.1 (side surrounds only) in my apartment even though I had the speakers and receiver for 7.1 because I found that with a pair of QS8s in that particular room rear speakers were completely unnecessary.

In summary I would move the rear M3s up and try them as wide speakers while moving the side ones back (or seats forward temporarily) to get a phantom rear effect from your side surrounds. Ideally I’d upgrade to QS surrounds.

Otherwise if you mostly have people watching from only the rear couch I’d leave the rear speakers. If you usually have people sitting in the side couches I’d mover the rears to the height role and again adjust the seating forward or side surrounds back to get a phantom rear effect at least for your back couch.

Hope this helps. In the end the only way to know what will work best for you is to experiment but I’m pretty confident you will find the wides are more engaging than the rears in your room. Also I’m 100% confident you would find QS speakers more engaging as side surrounds in your setup. I'm sure others who own them will concur

Cheers,
Dean


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