Possible To Use KPA For Effects w/Tube Amp?

No sweat. The real question is, would you like to use the Kemper's stomps in front of your amp or not?

Kemper just in the loop:
Amp effect send --> Kemper input
Kemper output --> Amp effect return

Kemper with stomps in front of the amp as well (also known as the Four Cable Method, you can find a bunch of stuff about it on Google):
Guitar --> Kemper Input
Kemper Effect Send --> Amp Input (put the Loop effect in either D or X in the Kemper, ideally)
Amp Effect Send --> Kemper Effect Return
Kemper Output --> Amp Effect Return

Just turn off the Stack buttons to hear the real sound of your amp.