Following this thread quite some time now I'd like to point out something which has allready been mentioned.
Did you compare the sound of the Kemper with your beloved tube amp being miked up? That's what I started some time ago before I finally got my Kemper. That's sort of the benchmark to me. I spend a lot of time listening to Musik through my Studio Monitors and playing along - Withe the "miked" up sound of my Kemper (and sometimes of my tubeAmp+pedalboard). Sometimes I add obe of my guitar cabinets or a pair of DXR10s. Volume level is very low (most of the time).
And another thing:
If you're using the guitar cabinet I qould estimate that it would not point to your ears directly but mor to your knees. That makes a huge difference.
Good luck on your yourney!