Crossover Options for JL Audio F110 subs

As a follow up to my previous inquiry on adding a pair of Fathom F110 subs to my Focal 836 mains. My listening room is fairly small at 11x14 and feel to 10" drivers will be fast and adequate for my room. I have come to the conclusion that the only way to achieve the benefits of improved dynamics from my mains and reduced load on my ARC Ref 75 is through the use of a external crossover. The NHT X2 seems interesting with balanced inputs/ high pass low pass variable output but the low price point concerns me. In order to minimize any loss in transparency, should I lean towards higher quality units equipped with 4th order Linkwitz-Riley filters? I am currently considering the Marchand XM9L with interchangeable frequency modules. JL recommends crossover point at 80hz which seems quite high. I would appreciate feedback from anyone that has used the Marchand crossovers and at what frequency setting provided the desirable results. Thanks