First of all, good work on the current project. I've been using Subsonic recently, and there is no better alternative out there! Thumbs up!!
However, I have an idea to even improve Subsonic. I noticed you're using JW player to play the MP3 files. I've done some things in the past with "Soundmanager 2". It's a javascript library to play MP3 files. It still uses an invisible flash file to actually play, but the interface is controlled by Javascript.
This has a few advantages:
- Allows you to build your own interface (especially if you know javascript and no flash

- It supports analyzer data
- Read ID3 tags (which is probably not needed in this case, but still)
Last but not least, it allows you to control the loading. For example you can start preloading the next song if the current song is complete (but still playing) from the playlist.
I could do this very easily if it was a simple website, but in your case I don't know how the HTML is formed...