... interface Superior quality FCC,CE,RoHS Short delivery time 4-in 4-out usb midi interface Model:W-819 Product ... 1. Used as USB MIDI with 64 channels, 4 input ports, 4 output ports, user choose the input port and output ... port 3 input port and 3 out port, 4 input port and 4 out port; 3. Can be used to ... between input 1, input 2, input 3 and input 4), four ports output synchronously Update Date:2011-11-8 ...