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

I am trying to do this: route some of my midi channels to sub1 only 
so that I can use an external efx processor - I don't want to reroute 
anything back into the XL.
In the mix output I set the channels I want to send2->sub1 and indeed 
there they are on my mixer, sans efx.
The problem: the selected channels are still being sent to the main 
outs as well as sub1.
I know this must be easy, but????????
thx
Dana