Can't help you with the sound, but I do have a question...
Did you get USB networking to work? I am using Midori Linux and a USB 10/100 Ethernet connector, and have no problems connecting to the Internet. Last time I looked, BeOS didn't have network USB drivers. Of course, it's been's long time since I looked! I would be VERY interested to know what you did.
Also, is your installation in Flash or is it a hard disk installation? One nice thing about Midori Linux is that the entire image (including browser, MP3 player, VNC client, and graphical text editor) fits within 16MB with room to spare.
I played with BeOS a long while ago, and it was pretty cool...