... usb midi interface Superior quality FCC,CE,RoHS Short delivery time 4-in 4-out usb midi interface Model:W-819 Product Description4 input 4 output USB MIDI Interface ... , support Windows XP, vista and Mac OSX. Through controlling the button, this new product can change between USB ... and Through modes as below: 1. Used as USB MIDI with 64 channels, 4 input ports, 4 output ports ...