What is Sonos f.ex?

Is the TV directly connected to the Amp, or do you possibly have the Amp connected to a cable box of some type?

The amp was designed so that audio from the TV comes in through the HDMI-ARC port (possibly via optical adapater).  If audio is playing from there, the Sonos app would say the source is TV.

If you have an audio source connected to the stereo RCA inputs, then that would be the line in source...which is not designed for use with TV audio.

I have the audio from the tv connected to the amp by RCA since i primarily use the apps on the tv.

Kinda seems to me that the tv sends out some kind of noice on the RCA and that triggers the “auto play” function on the amp. 

You absolutely should not be using the analog line in on the Sonos Amp for your TV connection.  This will never be satisfactory.  Connect the TV to the HDMI connector, preferably using the HDMI-ARC port on the TV.  If it doesn’t have HDMI-ARC use optical out with the converter.  The fact that you “generally use the apps on the TV” does not make it sensible to use the RCA and line in.  

Ill try that one out Thanks.

But why should i not use the headphone output on the tv to the RCA?

Well I assume you do sometimes use the TV to watch movies, not just listen to music?  The headphone socket will not handle the 3 front channels properly and the analog sound out is likely to be lower quality than you would get sending digital to Sonos. There will also be an audio lag.

Which TV apps are you talking about?  Music apps like Spotify?

The RCA line in is intended for purely audio sources like turntables. 

Im using it for netflix etc. Redused the timedelay to a minimum. Tryed out the hdmi choice now and it worked perfect. Thanks! :D 

I'm pleased to hear that. Enjoy!