ps Danny yes I indeed want to do something opposite of usual modifications,all so that I can actually use the Symfonisks. Why would that be such an problem if Sonos does not offer an out of the box solution..
I thought I already explained this. The speakers have no physical input capabilities. It’s not a question of morality, but physical capability.
I think your options are:
1 - turn them into passive speakers, connected to some other amp. Speakers would no longer be part of Sonos though (unless you use a Sonos amp), and you would control through the amp. You would need speaker wires connecting both speakers to the amp.
2 - Use a Sonos device that can connect to your TV (Amp/Beam/Arc) or does bluetooth sharing (Roam) and then group with the symfonisk speakers. The symfonisk speakers would be delayed though, and not play in sync with the video on your TV.
3- Do a UPnP solution as @chicks mentioned. However, I don’t think this would bypass the same buffer you would get with option two.
If you really like the idea of using picture frames as front speakers, and have no issues with speaker wires instead of power cords, that I probably would look at just making my own. The ‘trick’ to ikea speakers is really the use of acoustic fabric and low profile speakers. You probably can find low profile, or in wall speakers and build a simple picture frame with accostic fabrc yourself. You can power those speakers with a Sonos amp, or any receiver that can connect to your TV really.