Audio only broadcast to generic OS apps? Wirecast > Wowza > Itunes / WMP?

the only thing I can suggest is a module I wrote that takes a RTMP stream, strips audio if it audio/video, and then re-streams it to a Shoutcast server ( or another RTMP stream ), so that way you can have one RTMP encoder and feed into a server capable or supporting Windows Media Player (ASX file) or Itunes.

See

Shamrock