A few things to be said here.
First, neither the Five or Era 100 are designed to be used with your TV. By that I mean that they have a built in delay when playing audio to allow for proper wireless multiroom audio streaming. You’re likely to see lip sync issues.
Second, the Sonos adapter converts analog audio to digital. The Amazon adapter your seeing probably converts digital to analog...they are not the same thing. To my knowledge, no one but Sonos sells an analog to digital convertor dongle.
Third, the Era 100 has bluetooth and the Five does not, and if you want to try playing TV audio, that is probably the better way to go. I’ve done this with an Era 300 and found that the delay is not that noticeable. However, I rarely use the TV it’s connected to, and never for any real ‘serious’ TV watching, so it’s fine for my use case.
As far as which one I would recommend, the room size factors in more so that what type of music you listen to. I do not have the Era 100 personally, but find the Sonos One (similar) is great for small, mid sized rooms, particularly when adding a sub. The Five is needed for large spaces. That said, I might consider the Era 300 with sub if I was into electron music due to the atmos music capabilities. I’m not sure if much of your preferred genre is recorded in atmos just yet, but it seems like atmos would enhance it greatly.
