It's this box- about as simple as it gets. The ribbon uses a RJ-12 connector which is what old land-line telephones (remember those?) use - at least here in the US. I believe this box was intended for switching telephone lines.
The knob select 1 of 4 inputs that appears at the output. Each of my 3 ribbons are connected to an input and the output goes to the Kurz. I first tried some simple 2 to 1 "T" connectors that short each of the 6 lines of 2 ribbons together. It works but with long cable lengths funny things start to happen. Even with this switching box there is a slight glitch crossing between the upper 2 zones on the longer cable runs. Not surprising and not a big deal at this point. I think its more a capacitance issue than resistance.
This box is in serious need of a paint job.