Yes, it does. Beatstep's Midi adapter has a 2 contacts mini-jack, Beatstep Pro has 3. The third is for power supply.
The manual says that connector (black) is for clock synch which is not really what i'm after, i can synch the clock over USB. I want to send MIDI from one of the gray jacks to my Quadra Thru and power it by MIDI, will it be able to do that? My guess is no since it is a 3.5mm jack.