Emu XL-7 & MP-7 User's Group

Because each track can access all 16 midi channels on one interface, 
and/or all 16 external channels on the same interface (sending the 
same midi messages both internally and externally)

A real world example of this would be to have all your internal B 
channels devoted to drums, and have a different drum kit on each 
track, then programming a drum pattern using a hihat from one kit, a 
bass from another etc, etc, all on one track.