hi, I don't have an answer for you, but I do have a similar issue. I'm wondering if things gain greater traction if more people put their voice to it. so here goes:
I have a roku stick plugged into an epson projector. I have been using a wired in speaker for audio, but want to use my Sonos one. this has no cable in option, and doesn't use bluetooth for audio. I want to be able to send the audio from the roku stick to the Sonos speaker, I'm guessing by using airplay, but keep the video going through the projector - any ideas if this is possible and how to do it?
