Era 300 inside speakers not firing with Dolby Atmos

The Arc, Sub (Gen 3), and Era 300s setup is great for Dolby Atmos/TrueHD audio from films or music from both streaming or Blu-ray discs. This is the setup I have and I love it. The only big problem that remains is when adjusting the Surround Audio level in the Sonos app, the volume on the rear surround (inside) drivers on the Era 300s don’t change. This issue has been brought up to Sonos, but they don’t seem to be able to recreate the problem or fully understand it. But the problem does still exist. Is this a deal breaker? No. But if they address this problem it would make the Era 300s that much better as surround speakers.

The only other “problem/complaint” is the front facing driver on the Era 300s are disabled when they are used as surrounds. But this is by design.

Like @GuitarSuperstar I am happy with my Arc/300s/subs system. The main thing I’ve noticed is that, when playing Atmos test tones, the surround rear channels play at a fairly low volume from the inside speakers (which is where they are supposed to come from), but also from the top speakers. I have been unable to cajole anyone into verifying this finding. But it’s not that much of an issue. In a traditional surround system, the rear surrounds are behind you, and are usually pretty diffuse anyway The normal surround channels are placed to the sides and carry a lot of the action. With the 300s, the outside speakers are used for these “side” surrounds, so sound bounces from the walls to create the “side” effect.

• would 2 gen 3 subs be better than 1? if yes wherre to place them optimally ?
• would 4 era 300 (2 back, 2 side or front) be better than 2 era 300 alone (back) ?

1. by definition, yes. Placement would need to be decided by your physical room setup. There are lots of threads where optimal sub placement is discussed. @buzz has generally excellent advice there. 
    
2. No, the maximum number of speakers in a Home Theater Sonos setup is one soundbar, up to two subs, and two surrounds. Additional speakers can not be added to that ‘room’. 

dasus,

A general rule is that SUB’s should be placed vaguely in the same plain as the front speakers. This will yield the best overall blend of sound. Bass is not very directional. If you were blindfolded, then seated in the listening position and asked to point to the subwoofer, your accuracy would be poor. If the subwoofer is placed in a corner behind your position, your pointing accuracy would improve. Overall, you should go for the blend. In my opinion, if you can immediately and accurately point to the subwoofer, it’s in the wrong location.

Subwoofer placement is very room dependent. A poorly placed subwoofer(s) will not be very effective. Corner placement is most efficient. Mid wall placement efficiency varies almost inch by inch.

If you are a bass freak, two properly placed subwoofers is the way to go.

Only you will know what is “best” (for you).

• I have a very high ceiling, is it better to use wall mount for sonos era, or floorstand ? how much space should there be upwards? or it doesnt matter and you should just place it at the level of our earrs when seated in the living room sofa ?
• What (high end) HDMI cables should I use to transmit optima signal from blueray/PS/.. (earc) to an oled tv LG G3 tv ?

again thank you for your replies ^^