You SHOULD do it that way!!!You could also consider switching so that output 2 is used for your power amp and the XLR's are for the PA?
At the end of your signal chain in the axe you make a separate path that goes to a cab block and to the FXloop. That way the signal is send through a Cab IR and out to output 2.
You could also consider switching so that output 2 is used for your power amp and the XLR's are for the PA?
Jens
This was written for the II but I think everything is the same for the Ultra.