@Goslow, I also play a Kronos and a Nord Stage and had some complaints from our FOH mixer about my leveling. So just yesterday I did this...
On the Kronos you should have your entire set programmed via the set list feature. Each spot in the entry in the set list has a volume level that can be set independently of the Combi or Patch. That it, it only applies to THAT spot in the set list.
What I did was a plugged everything into my DAW and put a huge meter up on the screen and then I started by setting the volumes on each set list entry so the meter was at unity (0 db).
That's a good starting point. But then I went through the list again and tweaked individual entries in the set list by making solos SLIGHTLY loud (it's too easy to go overboard) and by making background parts (like pads) be SLIGHTLY lower.
In my personal experience you never want to "bump" the volume up or down by much more than 10 units (the scale is 0-128). I think if you do that, you'll find your FOH guy will not like it.
But another problem you may face is that often what you want to send to FOH is different than what you want to send to your personal monitors.
To automate that is very difficult and expensive. But what I do is I have an inexpensive little line mixer (mine is a Yamaha MG06) that sits on my Kronos and just allows me to RAISE my minotor levels independently of what I send to FOH.