Just a few thoughts.
Without having heard one so far, I would check if NAD has anything that would check most of the boxes. crutchfield does offer a return period so you can check how well it suits you and your speakers.
I am not sure if this is what you are looking for, but NAD D 3020V2 specifications mention...
"The sub output is equipped with a 100Hz low-pass crossover."
They also have NAD D 3045 model but check if it has what you want.
Both are well under $1200.
By the way, many people play speakers with impedance like yours with less than 100 W amplifiers with good results. Although Watts are Watts, do not get stuck on their number quite yet. Home trial will resolve your doubts, one way or another.
