If you have to use the soundbar as the center channel then you would connect a speaker to line level converter to the center channel speaker terminals of the HK. Connect both pair of wires from the converter to the 2 center channel terminals. You would then connect the output of the converter to the aux input of the soundbar.
You will need to leave the soundbar volume set and use the receiver to balance the channels and adjust overall volume. You may have to turn the soundbar on everytime.
If you have to use the soundbar as the center channel then you would connect a speaker to line level converter to the center channel speaker terminals of the HK. Connect both pair of wires from the converter to the 2 center channel terminals. You would then connect the output of the converter to the aux input of the soundbar.
You will need to leave the soundbar volume set and use the receiver to balance the channels and adjust overall volume. You may have to turn the soundbar on everytime.