hello !
here is the answer i've got a long time ago when i asked kemper support for connecting my RC10 to my stage:
« Please try to connect the effect as FX Loop.
Place the FX Stereo Loop effect in the "Rev"Module (last slot of the signal chain)
use the Send 1 and Return 1/2 to place the Effect in the signal chain. Make sure use upper Loop is checked (soft button 4 in the effect menu)
Use the Monitor out ( output source set to master mono) to feed an external power amp and a cabinet «