NHT Xd Notice D'utilisation page 21

Set bass management
Start with the XdW gain control set at 'just right'. Adjust up or down for the
amount of bass that sounds right in your room.
Music System - Two Channel
If you are using a stereo preamplifier you are done, enjoy your system.
Surround System (basic 5.1)
On your surround processor or receiver; set the front left and right speakers
to Large, set subwoofer to None (or Off) and set center channel and rear
speakers to Small.
For more information on different system configurations, check the website.
www.nhtxd.com/xdsetup