Still, a Kemper with a Kab will not be making anyone smile at whisper levels. You need to move some air IMO.
I am an electrical engineer ..... I don't believe in "magic" associated with tubes, transformers, or cab speakers
As with all things, this is just an opinion.
I am computer science engineer, I also don't believe in magic, I don't believe in anything except myself By "magic" I meant non-linearity of tubes. I had Kabinet, both with Class D poweramp and 50W tube poweramp (Fryette PS2) and it sounded not much different to DXR10. Maybe better utilization of imprints, but the imprints also worked on DXR10. But I couldn't get any Amp In The Room from Kabinet, even when feeding signal with tube poweramp. Maybe the Kabinet is just to shallow and light, I have no idea.
As with all things, this is just an opinion.