What are my options for multi-room audio?
If you can run wiring to the rooms easily, I'd recommend going with the centralized stack-of-amplifiers approach. It's very cheap, easy to set up, probably has the best sound quality, and is the most reliable. 

IR repeaters

Start by placing all the stereo receivers in a centralized location (I picked the laundry room). Then, install an IR receiver everywhere you want to have control over volume and source. I like these ones  since they're cheap and stick onto anything, however, you can get really nice units that have Decora plates that look very professional when installed. Don't worry about sticking with one brand -- all the systems are interchangeable. The only think you need to provide it is with 12V, ground, and a signal pin.

Routing the IR receivers

They usually have a 3.5mm stereo (i.e., headphone) jack used to carry these three signals -- so to run them back to your storage room you could either buy really long headphone extender cables, cut off the 3.5mm connector and splice in a cable, or build your own cable with a 3.5mm jack on the end.

Connecting everything together

Once you run all of these different IR receivers to your centralized location, you simply tie everything up into a parallel bus, i.e., connect all your 12V wires together, connect all your ground wires together, and connect all your signal wires together.

Usually, you use a connection block like the one in this kit to accomplish this goal. All it does is connect the IR receivers to a power source, and route their signals to the IR transmitters. The IR transmitters (termed "IR blaster" in the industry) get stuck onto all of your devices (amplifiers, signal sources, etc). 

This may sound complicated, but it's very simple -- you can have a dozen or so IR receivers hooked up in parallel to one connection block, and you can tie multiple connection blocks together.

Understanding how the system works

The signal line is pulled up to 12V by pull-up resistors in each receiver. When you start pressing a key on your remote control, the IR receiver receives this digital code, and pulls the signal line down and releases it back and forth to generate digital 1s and 0s. This is what allows multiple IR receivers to be wired in parallel, but it also has some known limitations

One more thing

It's nice to have a centralized location, but remember that as long as everything is on the same IR bus, you can control anything wired at any point in the bus. For example, instead of just hooking up the IR receiver to a cable running all the way to your centralized location, you could put another connection block right there in the room with it, put some IR blasters on the DVD player or TV you may have in that room, and then continue to run the signals back to the centralized location. This allows you to control those appliances from anywhere in the house. This may be useful if you have kids that blast music too loud, too late. All of the sudden, you can turn down (or turn off!) their stereo from your room. It sends a message.

Known Limitations

Since everything is on one bus, the system doesn't "know" which room the command came from, which means if you have a stack of Sony receivers that are all the same brand, then any time you use your remote control, it will affect all of them.

If you want to be able to control multiple same-model receivers independently, instead of wiring all the signals to one connection block, wire them to separate connection blocks.

Audio Path

Alright, you have a stack of receivers -- and I assume a stack of signal sources. Obviously, if your stereo receivers each have multiple inputs, you simply route the output from each signal source to one of the inputs.

Most audio sources don't have multiple outputs, however. You may find that you can simply use Y-cables to split the output of each source to drive your different stereo receivers. However, you may notice poor audio quality when you do that, depending on how your sources and amplifiers handle output impedance and input impedance.

It's not really important to go into, but basically, if your amplifier "loads" the source down, then hooking multiple amplifiers up to the same source is going to load it down more. The source is "expecting" to only be loaded down so much, so if it's loaded down too much, your frequency response may get wacky. Don't worry! You won't damage anything. But it may not sound as good.

This is highly unlikely, given that most audio sources have MOSFET output stages that don't have any series resistance, i.e., they have no output impedance, and can drive dozens of amplifiers without any issue.

However, if you do have issues, buy an audio distribution amplifier, which is designed to take one signal source and drive it to multiple stereos.

Miscellaneous Thoughts


This also works great with video -- you can put TVs in multiple rooms, and run HDMI-over-ethernet back to a centralized location
Don't think you can't get a high-tech computer-based media center into this action; I use a Windows Media Center USB-based IR receiver that I've got an IR blaster stuck onto. I bought four Windows Media Center remotes and put them throughout the house. You can control the music or movie from any spot in the house
Obviously, you can use any remote control you want -- if you want some fancy touch-screen business, go get a fancy touch-screen remote control. As long as it can send IR signals, you're good to go.
I'm getting a PhD in Electrical Engineering, where I'm working on Wireless Mesh Networks and high-tech stuff like that -- but I still know wires are always better than wireless. Because of its simplicity, this system never crashes, and never needs to be taken care of. It just works.