Hi

Anything is possible.

However, Sonos nor any 3rd party (that I know of) manufactures a cradle to hold the Era 100’s in place when mounted horizontally. The only thing I can think of would be wall attached shelf with a “stop” in front of the Era 100 to prevent it from rolling/vibrating off the shelf. However, no one knows what affect mounting them horizontally will have on the tonal quality  Also, mounting them below ear level (even mounted correctly) will most likely be a negative as far as surround sound is concerned. However, I have no evidence to say that I’m correct in my assumption.

so, i have to try them! If I like the effect I’ll think how to fix them: correct?

Yes.