I found an EQ graph for the Fender Twin Reverb amp.
It shows a large dip in the midrange frequency range.

So, when I dial in my new amp, I start by turning all the knobs down.

On the Bass (normal) side;
- set the volume to 4 or 5.
- set the midrange to 8 or 9.
- set the bass to 4.
- set the treble to 4 or 5.

On the melody (vibrato) side, I use a similar setup and set the reverb to 4.
I've attached a similar graph to this post, to help explain what I mean.

no substitute for the real thing, I love my old vintage amps/instruments, and analog tape machines/processors, I would not have it any other way

That's very true. My two JC-120 amps are the same way. You can hear all of the subtle nuances in the tone that are hard to replicate with digital devices. I'd like to try out the Kemper and see if it can truly replicate an amp. I know that it will just be a snapshot of the current settings, but can it actually capture all of those subtle nuances.