Its interesting as I think this is the same with guitar cabs...this "missing element" also adds restrictions/smoothing...
I use a powerhead with a real guitar cabinet V30s. I sometimes shut off the Kemper power and use the SD 170 instead which still sounds very similar to the power supply on the Kemper powerhead. If I use a tube poweramp with that same V30 setup, its a totally different ball game, but again many profiles do sound the same. If I use an FRFR speaker with the Kemper power section, that adds yet another huge change in tone to what the same profile sounded like the other way around. Many options to be had with the Kemper.