The USB has no audio output so you have 2 connections to make. Most likely why I haven't seen this sort of device. However any good home electrical wizard armed with a solder iron, a few select parts could make such as a weekend DIY project.
I am looking for a speaker system specifically designed for the first genertion ipod Shuffle. I would like one where you can dock the iPod Shuffle directly using the built in usb connector. I would also like to be able to charge iPod.
Thanks in advance for your help.