Originally Posted by Lethean
Can you explain the photo?
Are you standing in front of the TV looking out into the room?
Or, is the TV on the left?
Clearly the sofa is not centered on the room, so best guess from whatever you consider the prime seating location, how far is it to each side wall.
Though speaking metaphorically, it seems you are more interested in bring the Lightening than the Thunder from these additional speakers. By that I mean, you aren't interested in enhancing the deep rumble of movie sound tracks. Rather you are more focus on mid-range and treble - voice, general ambiance, fine detail, etc....
In that case, Di-poles could potentially work.
If you can put them far enough back and to the sides, then common bookshelf on stands would work. Bookshelf could also be mounted on the walls.
I personally am not that comfortable with speakers that have a low response of 100hz or above, but pretty much all of the small Lifestyle
Satellite speakers are going to fall in to that range, and there are millions of those sold every year.
Though there are many guiding guide lines. If wall mounting some say the Front should be ear level when sitting and the Side/Rear should be between chest level and ear level when standing.
The main thing you want to watch out for is that one of the Surround speakers is not firing directly into someone's ear. Their experience will be dominated by that one speakers. If the speaker is placed up higher, then it will not be directly into the ear, and the sound will have a change to disburse and give everyone somewhat uniform sound.
The same if the speaker are behind the sofa on stands. If the are literally directly behind the sofa, individual people are going to have their experience dominated by sitting directly in front of one of the speakers. But, if you move the farther back, the sound has a chance to spread out and give everyone a more uniform sound.
Though unconventional, we are all slaves to our circumstance. I have heard of people laying bookshelf speaker on the floor behind the sofa pointing straight up at the ceiling. Again, it a tight space, this would give individuals a more diverse sound.
So, it is a matter of what you can make working in your space. How much money you have to spend. And, what compromises you are willing to make.
But keep thinking about the sound from the Surrounds spreading out and given everyone the most uniform sound possible within the limits of your room.
Don't be concerned about the speakers not being equal distant from the Prime Seat. When your run Set-Up on the AV Receiver, it will balance the speakers for uniform sound at the Prime Seat, which is where you place the Microphone during Set-Up.
Every installation is tricky. But we make the best compromises we can to meet out needs and to serve our circumstances.