how are these different from using USB on cdj's? same same... actually, using USB on CDJ's is the stupidest idea in the first place. why spend all that money on buying (essentially) a CD PLAYER just to plug in a HD or USB?? isnt that what MIDI controllers where made for anyway? I wouldn't call it the stupidest idea. Why do car audio head units support cd's, dvd's, bluetooth and usb devices? Its useful to have the flexibility to use whatever medium suits the circumstance. yeh i guess you have a point there...