I'm looking at the sketch from post#2 and I think this is where the DP21 comes into play. I think you need to connect the 5th cable on the bottom of the 44 to one end of the 21 and connect the 77 cable onto the other end of the 21. Finally you would connect one cable from the bottom of the 21 to the 44 power supply which would connect to your receiver. I think that's how it would work but there's a chance that I could be wrong.
EDIT: I forgot that if you have a dual-tuner receiver, you would need two 21's. On second thought, if your receiver is a dual-tuner, use one DP34 instead. I'll post another pic in a moment.