best bet is to get another airport express. the extreme doesn't have any audio-jacks for use with speakers. the express is alone with this feature.
USB dongle? I wonder if you used a USB audio dongle/interface (eg. Griffin's iMic) whether you could use AirTunes with an Airport Extreme. (I'd like to know, I don't have it set up yet.)
I had exact the same question in mind... I thing that qua hardware it's OK. (USB > 3,5mm jack), but I'm not sure if iTunes (or other software) support this... Anyone knows this?
It will not work. There ARE other wireless audio systems on the market. But this time Apple's is actually about 1/2 the price of the others ones. Keep an eye on ehte Apple refurb store Airport express units show up there now and then. The other idea is to simply pull a wire. People tend to forget about wires. You can pull a wire to any place in a typical house for about 2 hours work. I'd work two hours to save $100. A four foot lonf flexible drill and a 50 foot fish tape makes the work go very fast. If you were to hire a phone installer he's charge about $100 an outlet. same as the cost of the AP Express -- and YES it's true Cat-5 wire is great for audio signals. It was actually designed for that purpose