I know I can make an iTunes server, add it in iTunes on my MBP and then control it with the Remote App. But I want to remove the laptop from the equation. Is that possible?
If you mean sending music from your iPhone to speakers attached to your APX, that is what Airplay is for. While connected to your APX's wireless network, you will play music in the iPod App, that shows an Airplay icon that allows you to select your APX as your speakers.
I want to put my MP3s on the external drive connected to the Airport Extreme, make an iTunes server to serve those files, then I want to play those files on my iPhone directly from the server, WITHOUT going through iTunes on my laptop.
I want to put my MP3s on the external drive connected to the Airport Extreme, make an iTunes server to serve those files, then I want to play those files on my iPhone directly from the server, WITHOUT going through iTunes on my laptop.