linux audio server for multi room audio possible?

when you say multi room, do you mean one computer with many audio outputs going to many rooms, or many computers in many rooms? for the first, linux has JACK audio plugging which permits you to redirect various audio streams to various outputs very easily on the fly. for the second, you need to look into PulseAudio which will allow you to setup sound daemons on a number of computers and allow you to browse the available daemons and play to whichever one you want. good luck if you work with pulse, its great software but not very friendly to newcomers

Slimdevices has a small network attached media player called the squeezebox that works perfectly in this role.

The squeezebox can play either independent audio or synchronized audio (same music in every zone) and can run off of a freely available server that runs on linux, windows, or mac os x.

The squeezebox is designed to work like an audio component, so it connects to a local amplifier/receiver in that room and only connects to the server via wired or wireless ethernet to get the music and track information. The whole thing can be controlled either with the included remote (or any other universal remote) or directly from any computer, PDA, etc. on your network by using a web-based interface for the music server.

Depending on how fancy you want to get, the only down side is that it doesn't support any sort of TV out for browsing, so you won't get anything fancy from it like coverflow anytime soon. The up side is that it doesn't require a TV to be on in order to select music.

It's definitely a cool product that's worth checking out if that type of solution works for you. I've got two and while I don't listen to music nearly as much as I wish I could, it's certainly no fault of the squeezeboxes.