Probably.
Here is an XLR connector.
Now your Behringer unit has balanced xlr and 1/4" inputs and no unbalanced ones.
Now your receiver is unbalanced and so is you sub.
So the lines have to be floated in and out of the Behringer.
So the live pin of the RCA jack coming out of your receiver need to connect to pin 2 of the xlr or the tip of a 1/4 inch plug. The screen needs to be connected to pins 1 and 3 of the xlr or the ring and body of a 1/4 inch plug.
Now when you go from the Behringer to the sub it is best to use a balanced cable (2 conductors and screen). Connect the live conductor to pin2 xlr or tip of 1/4 inch plug. Connect the screen to pin 1 of xlr or body of 1/4 inch plug. Connect the other conductor to pin 3 of the xlr or the ring of a !/4 inch plug. At the sub end connect the conductor from pin 2 or tip to the live end of the RCA. Connect the cable from pin 3 (or ring) and the screen to the shield of the RCA plug.
You will always get the best signal to noise if you combine pin 1 and 2 at the input.
Commercial cables vary and it is best to make the cables yourself, then you know it is right.
If you get hum after that, and you might, then your options are to use highz/lowz transformers in and out of the Behringer, or lift the ground of the Behringer unit.
The type of lines I described are called floating lines, and are the correct way to go form unbalanced to balanced and balanced to unbalanced.
Unfortunately mixing balanced and unbalanced equipment often gives rise to problems. Decent units should have balanced and unbalanced connections. Balanced systems in domestic equipment often leads to these types of problems.