Explaining the need
My husband and I tried to find a solution that will work for us for over 6 months. We researched many products, from Boxee running on a PC, to Sonos, to Logitech's audio line. But none comes close to our needs than Apple TV and MPD. Here are our needs:
1. No streaming. The music must be stored in a living room device, for the best "appliance" experience. If another PC or server had to be ON, at another part of the house, that was less than ideal: we wanted to be able to turn OFF all the devices used easily and fast (and without having to get up of the couch). Just like with an appliance.
2. Visual remote control. We're lazy in this house. We don't want to get up, go close to our appliances, just to view a small screen and change to another artist (e.g. with an iPod/Zune-out solution). And we don't want to turn ON our TV to do that either. So the remote control had to be "visual", like the iPod Touch's interface. Change albums/artists and scroll through thousands of songs very quickly, just by sitting on your couch!
After lots of consideration, the Apple TV and the MPD solutions were closer to what we needed. Hence, this article.
The Apple TV is simply a headless server, serving music to our Yamaha amplifier and speakers, and is controlled via an iPod Touch. The Apple TV is connected via Ethernet on our main PC, which runs iTunes and syncs the Apple TV occasionally. iPod Touch is remote-controlling the Apple TV via the Apple "Remote" application.
Price: $230 for the Apple TV, plus $200 for the iPod Touch, that comes to about $430.
The MPD server runs on a netbook with 160 GB of hard drive in it. Output is coming from a USB sound card via Line-Out (not headphones-out). Any old PC that is able to run a modern Linux distro can also do the job, as long as your sound card has a proper line-out (e.g. S/PDIF). Any web interface, application, or iPod Touch, or Android phone can remote-control the MPD server.
Price: If you already own an old PC that you can put to good use, and you don't mind using a PC interface, the price is $0. If you must buy a cheap netbook, plus an iPod Touch, plus an external sound card that features an S/PDIF port, plus possibly an external hard drive, the price can go up to $600.
In terms of price the Apple TV wins if you must have to buy the various parts from scratch, but the MPD solution wins if you already can put old hardware into good use.
Installing the Apple TV is fairly simple. You just connect its power, Ethernet or Wi-Fi, audio-out, and a video cable. The Apple TV requires to be connected to a video cable, even if you are only going to use its audio features (otherwise it will fail to start up). Then, you just sync your iTunes library to it. The Apple TV comes with 160 GB of drive, but hacks exist online to upgrade it.
Then, you just control it via the iPod Touch or iPhone, or iPad ("Remote" app in the App Store). The Remote app let's you do everything you need to do with the music side of the Apple TV, except rating songs, and turning off the device. Since we're using the Apple TV as a headless server, we found that if we blindly press the "menu" button three times, and then we long press on the "play" button on its original remote control, this will turn it off.
On the MPD side, you need to first find packages of the latest version, which have some important bug fixes (there's a third party 0.15.9 package on Launchpad for Ubuntu, for example). After installing, you must edit the /etc/mpd.conf file and set up directories, and permissions. Unfortunately, changing the MPD user to "eugenia", it would result in an error, MPD telling me that my music folders are not directories (which of course they are). The only workaround I found about this error online, was to chmod 755 the whole /home/eugenia/ folder, which is of course a major security hole.
Another problem I got with MPD is that it defaults on ALSA output, and the volume controls on MPD clients don't work. To add volume control you must write some of these crazy ALSA scripts, which I personally refuse to do on matters of principle. As for switching from ALSA to Pulse Audio, this apparently creates some instability.
On the upside, MPD supports scripting, which can extend its functionality. Apple TV can be rooted, and add some functionality too, e.g. support for OGG etc. Additionally, MPD can stream online radio, but so can the 3.0.1 version of Apple TV.
If you already own an iPod, then chances are that you need iTunes. Sure, there are Linux plugins for iPods, but none can do all the things that iTunes can. And speaking for myself, I simply can not listen to music without "ratings" and smart playlists. In fact, all our playlists at home are based on "smart" criteria, and absolutely none of them are just collections of similar music, or playlists that we simply created randomly "cause it sounded good together". MPD does not have this ability. I guess we're a bit too particular in our home.
On the MPD side, I had to create an SMB share from my Windows machine, and pull inside all that music to the local MPD drive. Unfortunately, while this works great as a first time, I can't sync any new music I buy from Amazon or iTunes to the netbook/PC running MPD. And having the main PC "ON" at all times just so I use its SMB share as MPD's music database is out of the question. I need a "clean" solution for my living room, and asking having my main PC in my office "ON" just so I can listen music to my living room, is not acceptable. What's needed here is the ability for MPD to sync with iTunes remotely, and possibly other popular media players too. Truth is, more and more people are buying music from iTunes or Amazon online, so some sort of syncing is needed (by default, without having to hunt down plugins).
Also, there's no way to put the PC to sleep when you're done with MPD, short of getting up from the couch, reach the MPD netbook, and close its lid. Or run VNC on your controlling device, and try to induce sleep to your MPD PC/laptop that way.
In terms of number of clients, MPD has the upper hand, but for the scenario I'm presenting (living room usage), I find that a smartphone, or a tablet is much more desirable to a full PC/laptop usage. The MPD client for Android is not very good, and neither is the iTunes one (Apple TV does not work properly with any of the 2-3 iTunes Remote apps for Android, since they're all based on the same source code). On the iPad/iPhone/iPod side, both the MPoD client and the Apple Remote apps are well-written.
For the kind of scenario my husband and I are interested in, living room usage that is, the Apple TV does it better for us. Since we have iPods and we're using Amazon/iTunes to purchase our music, it makes more sense for us. The experience is more solid, coherent, and "appliance-friendly". Both installation and usage is worry-free.
On the other hand, MPD is a better idea for different scenarios, e.g. on a corporate environment where all employees can listen to the same stream. Or if you never leave your office, so you listen to music exactly at the same time you're working, so you can use your main PC to control MPD. Or, if you don't own an iPod or want to use iTunes, in which case having an Apple TV makes little sense.