As a nubie, I have no idea what this means.
Thank You for contacting Onkyo USA Product Support.
In a satellite / subwoofer loudspeaker system, the higher frequencies go to each "satellite" speaker around the room, such as LEFT, CENTER, RIGHT, LEFT SURROUND, and RIGHT SURROUND. The lower, or Bass frequencies for EACH of the channels gets "steered" through a BASS MANAGEMENT circuit where it winds up going to the subwoofer only.
The speaker crossover for the DTR-5.4 pertains to the set up in the Digital and the Analog surround modes. The DTR-6.4 allow bass management in the "Multi-Channel" mode.