Hi @Sebkulu
Welcome to the Sonos Community!
So my question is: is 3 meters too far away from my couch?
The ideal distance for the Era 300s to be placed behind you is about 1.5m, so 3m is not so bad as you might think, considering most setup will probably have them placed mere centimetres back.
I would, however, be concerned that you may lose out on some of the effectiveness of the rear height channels (though this will depend on the height of your ceilings - they higher they are, the further back the speakers can go without losing the effect). Given that you have the space, I would in your shoes consider moving the sofa back a metre, assuming it’s possible (or permitted!).
Really, the best thing to do is try it and see - buy direct and you’ll get plenty of time to test before getting a full refund if needed. I think you will hear a large improvement over your current setup regardless.
More over, I’ll have to put them a bit higher than ears level otherwise there will be some obstacles in the way (table and chairs of my living room), will it still be all right for sound?
This will be fine, seeing as you said “a bit”.
There will be plenty of room around each of them though.
Great - this is what you need to make full use of the Era 300’s directional sound.
Thanks in advance for your replies and insights about my questions!
You are most welcome! I hope this helps.
Hi, and thanks a lot for your very extensive answer 
though this will depend on the height of your ceilings
My ceiling is 2m40 high, and the speakers will be placed about 1m70 high (1m above ears level when I’m sitting in my couch)
But the wall mount is able to provide some downards angle, so maybe that’ll do, wether it to be the direct sound from the front and sides speakers, or the upwards firing speaker, which is already angled at 15°
So with the angle from the wall mount, the upward firing speaker will be firing at 30°
buy direct and you’ll get plenty of time to test before getting a full refund if needed
Done, I just received them 
Great - this is what you need to make full use of the Era 300’s directional sound
Well, there are still walls on each side of them (about 20cm from where I’m planning to mount them)
