Never mind. I see that your receiver is a stereo receiver that probably has no bass management function.
Can't give you any answers to your original question. But I have another question, does your subwoofer have a built-in amp? If it does, what kind of crossover options are available through it? Some plate amps can take in the full audio signal, drive the subwoofer through a low-pass filter, and send out a signal, through a high-pass filter, to your main speakers.