Joel, I run whole house Airplay speakers, mostly through Airport Expresses, but also AppleTV and now I’m using a JBL SoundFly..
This JBL speaker is probably not what you want for your main stereo speakers, but it’s great for announcements. That is, it WILL be IF I can get the rest of the configuration done. ST sees it as a speaker, but I’m still missing parts of the setup and waiting to hear from the guy who wrote the code. See this link for all the gory details.