Hi, 

I recently purchased a Sonos Arc Ultra, a Sonos sub-mini, and two Sonos Era 300 speakers.

Although I purchased them together, I had to wait for the Eras to be delivered. I set up the Arc with the sub during that time, and it all sounded fantastic. I was really looking forward to the Eras arriving so I could set it all up as a Dolby Atmos sound surround system, obviously all in the same room. I have followed as many guides as possible regarding setting it up. I realize that I must be watching films and music that support Dolby Atmos, I stream music from Spotify and Amazon Music, as I was looking forward to listening to music with this complete music system. I listen to music all day, so it is important for me. 

Here's what I don't understand and need help. When playing music from Sonos radio it comes out of all the speakers front and back. However, when I play through Spotify or Amazon Music I can barely hear a thing from the rear speakers. 

And when watching a football game last night on TV, everything sounded very tinny. Have I done something wrong in setup?

On Amazon Music, while listening to an album being streamed in Dolby Atmos I can hear music some sound from the Eras, but very faintly. The same when playing a Blue Ray video in Dolby Atmos. I would like to hear far more from them.

As for setup, I used the Sonos app, via an Android phone, sadly I don't have an Apple iPhone. The Arc Ultra is connected via Ethernet.

So that's the setup, my questions are: Have I set up correctly, if not what else should I do? to get more sound from the back speakers, when streaming via music apps and watching TV.

Thanks in advance of any help.