• a WiFi bridge allowing a non WiFi computer to connect to an existing wireless network
• a WiFi access point allowing other WiFi devices to connect to a broadband router
• a wireless or wired print server

Pretty good value when you consider how versatile this is. The configuration software works by defining a set of profiles so you can switch between any of these usage scenarios quite easily.

However, it is as a wireless audio streamer that I am using the Airport Express. I have it hooked up to an old pair of active computer speakers in the kitchen. When I run iTunes on my main PC, a new pull down list appears in iTunes that lets me switch between my main PC’s speakers or the speakers in the kitchen. I assume that if I had more Airport Express’ in the house they would all be listed. The really cool thing is that if you switch speakers whilst a track is playing you get a slight pause but then the audio just carries on from the same point but coming out of the other speakers. So if I’m listening to a Podcast and fancy a cup of tea, I just switch speakers, run down to the kitchen and carry on listening from the same point. It is a real shame that you can’t play on more than one pair of speakers simultaneously. A remote control would be a nice thing to add to allow me to control iTunes with out having to run back upstairs but I can live with this as it is (actually my Nokia Communicator running VNC is a good substitute for a remote).

The box itself is really compact and the sexy iPod-white shell doesn’t look out of place in our kitchen (although the big green LED could be a bit more discreet). The power supply is built in and you plug the whole unit into a plug socket.

Setting up the Airport Express was a little tricky. The supplied administration software runs on my main PC so to get the Airport Express configured initially I had to connect it to my switch using an Ethernet cable. I then had to work my way through my WiFi security settings before I could pull the cable out and use it wirelessly.

Overall, despite already talking someone else out of buying one of these little boxes (sorry Kevin), I am really pleased with it. The smooth integration with iTunes is something you can only get from buying kit all from Apple. If I could stream to more than one set of speakers simultaneously I’d consider buying more and setting up the rest of the house.

I noticed that Apple and a number of other players have started to support a format called AAC or Advance Audio Coding. I had assumed it was just another proprietary niche format until I discovered that AAC is actually the audio part of the latest MPEG2 and MPEG4 video compression schemes. This gives it a lot more credibility in my eyes. I have a encoded a few of my albums at 128 kbit/s using AAC and I have to say the results are impressive. At 128 kbit/s sound quality is great and the file size is 2/3 that of a 192kbit/s VBR MP3 file.

One thing that is a little unusual is that AAC files can have different file extensions. We’re all used to mp3’s being .mp3, but I’ve seen AAC files named a number of things (.aac, .m4a, .m4b). iTunes names files encoded as AAC as .m4a. iTunes also recognises .m4b files as being AAC files but with allows the contents to be bookmarkable which is very useful for long-ish content like audio books or spoken word.

I’m not about to try and re-encode all my music from MP3 to AAC but I think I will now use it for any new music I buy.

More info on this subject:
Apple on MPEG-4 Audio: AAC