how to set up an apple network to stream music without having to leave a mac on

I will jump in and answer the part i know about.. but I do not use SONOS and don't even use itunes in a significant way.. so you will need to look deeper for other parts of your solution.

itunes is strange because it is not a server design.. this makes sharing it hard.. and that is deliberate due to copyright. Apple do not want you to simply copy your itunes for other people to use. So the library is linked closely to the player.

Moving the library has specific method. Apple documents gives you the method.

Of course this is really messy running a computer when you want to play music in lots of settings.. so a NAS is a better solution. TC is not a NAS.. it is a backup target for TM.

I (plus many experts here) do not think TC a suitable location for itunes library.

It has the following issues.. it is designed to be slow to spin up and fast to spin down.. Your computer will lose track of the library every time you boot or wake your computer. Streaming is difficult because the TC will tend to spin down the disk at the first opportunity.

2. It is easy to corrupt the library. Due to wireless connections many people use.

3. The TC cannot back itself up .. nor can TM backup network drives.

4. If the TC dies.. as they have a tendency to do.. your library is lost.. so backup is a serious problem.

Now the above does not stop people from doing it.. with varying degrees of success. never discount the backup problem. If you want to try remember this is not going to be straight forward.

A proper NAS has advantage of being able to back itself up.. it can also have spin settings fine tuned and higher speeds available as well as onboard data protection via raid.

But NAS is still not able to be backed up by TM nor is TM always reliable if backing up to it.. Apple made one and one only network target for TM .. the TC.

Your problem is far from unique.. a few seconds in google will give you loads of info.. even from the sonos forum.

eg http://forums.sonos.com/showthread.php?t=33468

Is this the way to go in trying to set up Sonos to play without having to turn on a macbook? Or any other suggestions?

Until Apple recognise the hole in their product lineup.. which is maybe deliberate.

A mac mini as a media computer/server (except itunes is not a server.). but you can build a quasi one. It doesn't need to be the latest .. a cheap second hand one say since 2010 should be more than powerful enough to do this role. Attach a large external drive.. not USB2 if possible.. that might mean fw800 or deliberately paying the extra for Thunderbolt mini and connections.

So I would have a mac mini with wireless capability and a large external HDD sitting somewhere preferebaly with fw80o or thunderbolt, and put my Itunes on there? I'm new to mac mini's, I assume I could just turn on the mini and access it through my macbook, or do I need to get peripherals (screen/keyboard) for it too? Then the TC would back it up to.

The mini does not need wireless.. and it will be better with ethernet to your main router.. whatever that is.

You leave the mini on 24/7.. there is no need to have a screen after the setup.. in fact you can setup remote access to it. The reason to use the mini is very low power consumption and good sleep etc as well as being Mac OS to keep the itunes in the preferred OS.

The details.. sorry you will need to look up.. as stated. I do not run such a system.

Either that or a proper NAS, and by "proper" I assume you mean one with RAID so one disk is backed up by the other one? So I use my TC to back up my MAC's, and just get a NAS for the library and point SONOS to the NAS. And have the NAS back-up itself. This makes my TC redundant because I could just as well back-up everything to the NAS... I have also read people attaching usb external HD's to an airport extreme or something, but don't these drives go to sleep and so would have to be woken up each time I want to play music?

NAS pretty much equals Synology or QNAP.. they are the main players. And yes.. I mean a raid. Disks do not back up each other.. but data is redundant across the raid. You still need a USB to backup. Raid still fail and you still need a completely different disk for backup.

TC still is the only Apple approved method of network backup for TM.. other units work but give trouble.. that includes USB disk on AEBS.. except for the latest Gen6.. where Apple give conflicting info. Like even they don't know.. one hand says yes,,, other hand says no.. !!

See http://pondini.org/TM/Airport.html

USB is slow.. and on an AEBS or TC read that super slow.. much worse than directly connected.. and there is no other options. That is why I am suggesting not USB for mac mini .. although let me qualify that with the latest one is USB3 which is fast.

Effectively btw the mini is simply replacing the laptop you use now. It is just a more suitable item that you don't need to cart away each day. And hence can use cheap large 3.5" hard disk. Don't get all in knots over the setup.. just think.. i am dropping in a mini to replace the current Macbook to do exactly the same task.. how you organise the library is entirely up to you.. you can and should have it on the mini which then backs up the TC.. this is the right way.. and cost wise if effectively the same as the NAS solution.. albeit does not have the disk capacity.