I hooked up the kemper to my peavey classic 30 today. I switched off the kemper cab and went straight into the peavey return jack bypassing the peavey tone stack so in effect straight into the power amp section.
This really comes alive doing this, absolutely fantastic. I recorded a short clip. I recorded this with an audix i5 mic about 2 feet in front of the amp and about 2 feet to the left of the centre of the speaker and also pointing upwards (I don't like the really close mic'd sound of any amp).
Anyway, not sure this does it justice but the sound in the room is fantastic. Using a real guitar cab certainly brings the kemper alive and it really is just like playing a real amp with the added bonus of on board effects etc. I tried this technique before with a pod hd500 and it sounded like crap, and I also tried this when I had the axefx ultra, and that sounded like crap too, but the Kemper straight into a power amp with a real guitar cab sounds fantastic. Your opinion may of course differ, but here's a short clip of it anyway.