integration

What value should I choose for the HIGH CUT knob on Yamaha? Revel specs: Low Frequency Extension 55Hz, 50Hz, 45Hz (-3 dB, -6 dB, -10 dB)

I'm planning adding a subwoofer to my system, but I don't want to use external DSP. Are there any guides I should follow in order to phase (/time) align the subwoofer to the mains solely by positioning and through the sub's own dsp settings (crossover, phase, etc.)? Can it be done? Thank you