Hallo …
Today Steinberg hosted the new update for Cubase SX/SL 2.2 wich now includes support for Mackie XT - Extension Unit.
Some Generic Remote Issues are already in there (Pan/EQ/Sends…).
See http://forum.cubase.net/forum/Forum27/HTML/000034.html
Have Fun 
Pearl
Hi folks,
the update workes great ! - No more coupling 2 Boxes. The XT option workes well.
You just have to pay attention to that the XT unit is the most left unit.
But still the same problem with the led vu-meters ! grrr
Looks like they still work horizontal than vertical.
greets Doc