The Sonos app on your Phone or Tablet is just a remote control for the Sonos system.  All the logic is held on every speaker.  The music comes from Music Streaming services or Network storage on you home LAN, NAS drive or PC Drive.   So the App is just instructing our Sonos speakers what to play and what source to use, the music information does not travel through the phone.  This is why you can turn of your phone or close the app and the music will play.

However...When at home and connected to your Sonos system, Sonos can play music stored on your phone, for Android you can use “Play from This Device”, but this means storing ALL you music on the Phone itself. 

When you are away from home or want to listen via headphones then you would use the phones native Music app to play those files or use the App for whatever streaming service you use.

As far as playing from where you left off, using Amazon as an example.  If you use the Amazon Music App to play music to your Sonos(Rather than the Sonos App itself) then you can just change the Device to Play and chose this Phone.

Hope that makes sense.

To add to the above, this is generally referred to as casting.  I’m not familiar with Mixcloud to know if they support casting, but the common icon for this is pictured below.  Again, you would start playback on the music service app, then while connected to your home wifi, click the casting icon and select the Sonos room you want to cast too.  When you are ready to leave the house, hit the casting icon and stop playback the speaker, which should then have the music service playing on your phone again.

If you start playback through the Sonos app, there is no way to cast audio from Sonos speakers to your phone.

@melvimbe @bockersjv 

Thanks for the suggestions.

For some reason I thought Mixcloud picked up where you left off on different devices, it appears I imagined it. So What I’m asking Sonos to do doesn’t happen on the native apps either :(

From the apps I’ve just tried:

 Deezer, Apple Music and Mixcloud, none of them cast to Sonos, only to Chromecast.

Are you saying that Amazon music can cast to Sonos? (Similar to Spotify Connect?)

My phone (LG V60) can cast whatever is playing on the phone but can only cast to Chromecast not Sonos.

I know Spotify can cast to all sorts but quality is still low on Spotify.

Media Monkey Android should cast to Sonos but doesn’t. Windows desktop Media Monkey can, but not to grouped speakers :(

Android Bubble Upnp can cast to Sonos but doesn’t seem to do Deezer,Apple or Mixcloud but it does do Tidal and Qobuz. I might did in to that and see if it solves the problem?

The Sonos app has its drawbacks but it’s nice for accessing everything in one place.

Hence my suggestion/wishful thinking of an app that can turn your phone with Sonos App into a “virtual” Sonos speaker. That would solve everything as you could listen to the “virtual speaker” via headphones / line out / bluetooth etc. But I guess Sonos don’t want that as you could use it for other wireless/wired speakers amps in your house and avoid buying Sonos speakers.

I know there are 3rd party apps like airfoil that can do this with Airplay was hoping there might be such a thing for Sonos??? 

Having 1 or 2TB of music on my phone wouldn’t be an issue. Happy to get a big SD card :)

If it solved the problem

Would be nice to just have a seamless clean transfer experience on to your headphones / car, rather than the faff of opening different apps and finding what and where you where up to on your listening habits.