Yes, this should be possible.
If the sound originates on PC #1, you run Broadwave on that one. With Windows sound mixer "Recording properties" you select Line-In assuming that the audio is being fed in there.
Then on PC #2 you use Winamp or similar client to listen to the stream from PC #1.
On PC #2 you also run Broadwave. On "Recording properties" select "wave out mix" or Stereo mix" (depending on your sound driver).
The "listening public" will then connect to PC #2 to hear the stream.