Just a small note.
During our LinuxTag 2008 adventure, some guy came to me, and asked how we achieved synchronization. And I told him, we don't.
After a bit chatting, he said, they have been trying to achieve synchronized audio for a couple of years, and still have not had success.
posde - exactly!
We've posted question on this to the Squeezebox forums and they have no real solution for this issue yet either. The Sonos guys have also spent years on it and they freely admit they cannot compete with a traditional solution. This stuff is not easy in way... and it is not going to be delivered by xine alone.