How can I have computer speaker show up as sonos speakers

There's lots of info out there about how to play computer audio to sonos speakers. What I want to do is the reverse(?) : Make my Mac computer speakers be available as sonos speakers on my network. So I can stream Pandora to my computer speakers along with my other sonos speakers. Can you do that?? Seems like a mac is smart enough to impersonate a sonos speaker... 😎