Akai MPC 5000 Reference Manual page 184

The MIDI page will be displayed.
The 'soft thru' field determines how to output the incoming MIDI signal. You can select the following options:
The MPC5000 will not output the incoming MIDI signal.
The MPC5000 refers to the MIDI channel setting of the sequence's track. The channel information of the incoming MIDI signal will be
replaced with the MIDI channel selected the track.
The MPC5000 will output the incoming MIDI data as it is from MIDI OUT A.
The MPC5000 will output the incoming MIDI data as it is from MIDI OUT B.
The MPC5000 will output the incoming MIDI data as it is from MIDI OUT C.
The MPC5000 will output the incoming MIDI data as it is from MIDI OUT D.
The MPC5000 will output the incoming MIDI data as it is from both MIDI OUT A and B.
The MPC5000 will output the incoming MIDI data as it is from both MIDI OUT C and D.
The MPC5000 will output the incoming MIDI data as it is from all of MIDI OUT A, B, C, and D.
The MPC5000 will receive MIDI from all channels, and play back MIDI on channels set to the received track.