Dont think i have ever seen anyone mention that they use a tech21 power engine with their kemper,are they no good?
I have used the PE with several modelers (Pod XTL and X3L) as well as sansamp pedals in the past.
While it's not a bad amplification solution it's not stellar either.
Pros:
Cheap
Lightweight
Looks decent
Reliable amplification, loud enough for most things.
Cons:
Not FRFR
Built- in Celestion 70/80 speaker is by definition a guitar amp speaker, sounds fairly neutral but a bit dull also.
The biggest disadvantage is that the unit is not FRFR, therefore nowadays I wouldn't recommend it for a modern amplification system for a modeller/profiler.