Joey Hess, a developer contributing to Debian GNU/Linux, has shoehorned a fully functional PC into a portable boombox stereo. Two USB ports are embedded in what used to be the CD eject button, and the computer’s LEDs are visible where the CD slot used to be. The tape deck has been repurposed to provide access to a 4-port USB hub. “Hit Stop/Eject to change USB keys. :-)” You can see a thumb drive sticking out from the tape slot in the photo above!
Hess has his minimal build instructions online, and reports that the work took him three days, for a total cost of under $100. The QNAP computer Hess used is no powerhouse, but it’s perfectly suited for the task at hand: feeding audio from a hard drive to the boombox’s speakers.