External power... that's the only option for it, actually. I may have used the wrong term when I said self-powered... I meant it had its own power supply.
On another note, Griffin has a product called the USB-Audio Hub, it's basically a USB hub specially designed for audio device needs.. whether it's just $40 overkill or not, we'll see, I might pick one up for the hell of it if I can find it locally (and a regular powered USB hub doesn't do the trick).