Exaggerating/minimizing variations in velocity
You can exaggerate or minimize changes in note velocity already recorded on the MPC. If you go to the VELOCITY on the Main Screen and Open Open Window, you get a velocity editing screen. You several options on how to change velocity, but one that is of interest here is MULT VAL%.
To exaggerate velocity differences, you set the Amount to a value over 100%. Of you have velocity values near 127 (the max) you may have to first subtract a value from all the notes before multiplying. The actual difference in velocity will only the increased by the amount you multiplying by:
One note vel: 50
Second note vel: 60
Difference in vel = 10
Multiply by 150%
New One note vel: 75
New Second note vel: 90
New difference = 10 X 150% = 15
If you don't like the new velocity level you can go back and Subtract a value from the new velocities, which will keep the new difference. You may also call this a rudimentary form of 'expanding' or 'compressing'.
The minimize the difference in velocity, just multiply by a value less than 100% and add value as necessary.