The XO should be based on the sub and speakers:
mains 50 Hz-20,000 kHz
center and surround 70 Hz-20,000 kHz
Sub 29 Hz- 180 Hz
xo range 70-180 Hz
in this example a range of 70-180 is acceptable. In general set the xo 10-15 Hz higher than the weakest speakers frequency range. Also try to stay under 100 hz unless this is a satellite system which may xo the sub at 120-200 Hz. Some subs don't do well over 80 Hz so it all depends on the speakers and the subs undistorted frequency response.
Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus 200 Five, Dayton 18 Ultimxa Dual Sub Cab(2), Dayton 18 Ultimax Large Vented Sub Cab (2), on Berhinger I Nuke DPS amps, Samsung BDP F 7500, Asus/My Book Live HPC 4 TB
Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500