If you only want to use the MPC2000 as a drum machine for now then don't connect your MIDI keyboard, sound module(s) or make any MIDI connections. If you choose to connect an external MIDI device connect the MIDI Output of your MIDI keyboard to the MIDI Input of the MPC and the MIDI Output of the MPC to the MIDI Input of your chosen MIDI sound source (MIDI Output provides an A or B option). If you want to use a sound source from your MIDI keyboard then connect the MPC Output to the keyboards MIDI Input, in this case it would be necessary to turn the Soft thru function off in the MPC (open window in track MIDI channel select on main screen). MIDI can handle up to 16 data channels, the MPC has MIDI Output A and B enabling it to handle up to 32 channels of data.