I think this is not clear:
There is only two sounds available by instrument: "Accented" or "not accented". Velocity will just change wether a sound is accented or not via the accent threshold settable in the MCC. It will not change the volume of the sounds.
Velocity is computed using the way you press pads when live recording a sequence: hardly, softly, etc.
Velocity is sent via MIDI/USB the way it has been recorded (using pads or MIDI/USB inputs).
If you enter steps manually, the default velocity is 100. If "accent threshold" is < 100, default velocity is "accent threshold" - 1.
If you enter accented steps manually, the default velocity is 127.
Regards,
Y.