I would and have used the 789-44's IR RCVR jack for a Xantech receiver. Don't mix brands.

Just as an FYI: Xantech used to call the 78944 the 789-44. Any time you search on Xantech's site, omit the dashes.

Now, a long FYI: The 78944 can be seen as two separate devices. One part, using the power connector and either the screw terminals or the IR RCVR mini jack, provides ground and power for a receiver and connects the receiver's output to the buss (those three screws). The other part connects to ground and the buss and runs the buss through a resistor for each of its four outputs. That is, there are four resistors.

You can use a 78944 just as a connecting block without any LEDs; in this case wires connected to the screw terminals let you send the IR buss elsewhere. This is the same function as the CB12, but the CB12 also has one LED output jack and is cheaper than the 78944.

Or you can use a 78944 with the IR IN and ground, run from another location such as that in the last paragraph, to send signals to 4 IR emitters, either double or single. Note that if you use the 78944 ONLY to distribute IR, and NOT to connect an IR Receiver, the power input on the 78944 does nothing at all.

Incidentally, never use two power supplies until we talk about steering diodes.