You might look into CobraNet - digital audio over ethernet.  Designed 
for professional multitrack recording.

http://www.cirrus.com/en/products/pro/techs/T9.html

I don't have any experience with it.

Also you've probably seen this already, but if not:
http://www.sonos.com/
great stuff.  a friend of mine has his house set up with it.  fun fun. 
not so cheap though.

Spdif @ 44.1Khz stereo is on the order of 2.8mbits/sec, I believe. 
(44.1Khz * 32bits/sample * 2tracks).  This could be sent via rs-485, 
over an unused pair in the ethernet cable.  How resilient the ethernet 
data is to this new signal down the cable, I couldn't say.

Anyway, interesting little project.  do post more as things develop.

J



Mike Hord wrote:

>>>An easy solution is to use Shoutcast from the creators of WinAmp. Run a
>>>Shoutcast server on the PC and a client in each place that you want to
>>>listen. I've used it to stream audio to multiple locations within my home
>>>and it kept the audio of all the clients in synch.
>>
>>One possible problem with that solution is that there are fairly large
>>buffers between you and the original sound source in shoutcast. So
>>basically, if you change the music playing on the shoutcast server,
>>it'll take a few seconds to hear the change. Could be very annoying.
>>
>>It's also why shoutcast simply can't be used as a cable replacement, for
>>say streaming live audio within a building. You'd be way out of synch,
>>by 10 seconds to as much as one minute in my experience,
>>intolerable in many situations.
> 
> 
> Which is why I discarded audio over Ethernet in the first place.  It just
> occurred to me that my little buffer box which converts the SPDIF to
> a more transmissible signal level could also have a multiplexer which
> would allow me to hook in a conventional audio signal from, say, a radio
> tuner.  Saves me the trouble of having a tuner in my PC and lets me
> distribute ANY audio signal I choose through my apartment.
> 
> Plus, shoutcast might not (haven't looked too hard at it) allow me to
> remotely manage my playlist and request new songs, while my
> system would.
> 
> Mike H.
> 
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist