Subwoofer setup for McIntosh MA6900 and Velodyne DD18

Expert advice, please:

I am setting up a subwoofer with my beloved Mac MA6900 + B&W Nautilus 804 pairing - the "newcomer" is a Velodyne DD18. The Mac has no subwoofer filtering but the DD18 has a sophisticated digital room correction and setup function which provides a fine-tuned hi-pass crossover curve, etc., but this requires me to run a long line to the subwoofer from the MA6900 and then another back to the Amp Input. The subwoofer claims 14Hz to 120Hz +/- 3db. The speakers go down to 45Hz +/- 2db and give an amazing soundfield and separation, but no slam/room lock, of course. hence the sub to try to get the best of both worlds.

So I have two options:
1. As described above, feed the subwoofer from Output 1 and use the subwoofer to control/filter the signal (which raises a mild concern about adding noise and distortion), or...

2. Let the MA6900 Output 1 stay as-is and feed the subwoofer direct from Output 2. In this case I would use the 30Hz equalizer to roll off the low end from my speakers and set up the subwoofer to manage the frequency response curve via its built-in room correction. (This avoids all risk of added noise to the main speakers, but loses the sophisticated hi-pass cross-over).

OK, what do you think?