Snips smart speaker with line in audio?

Hey snip-pros,

I think about using snips as new alternative smart HIFI for my flat.
What I wanna do is having a snips speaker that has a line in audio to connect different audio sources.

For example an old radio or a TV - in best case scenario the line in is dominat so the speaker always plays the source by default. Than you can have a mute/unmute command by voice control or a physical button. In addition to that the wakeup word is dominat and similar to Alexa the music is not dominat for the time you speak to snips.

So far I have not found any information about such a setup.

Thanks for all the kind people that might answer!