Pass XA30.8 vs Luxman m600-a vs Hegel H20

Nice choices. I would look at the pass and Hegel only - I am not sure the luxman is the same level imo.  then it comes down to what speakers you are driving as these are pretty different amps. If the speakers would be good on lower power, and you like class a sound, the pass would be great. The Hegel is probably more versatile in terms of matching to different speakers if you plan to switch over time. The Hegel also runs cool. But both are really top notch. Enjoy the search. 

Vermeer - i dont know that model of luxman so you are right - i shouldnt cross it off the list. Was based on general and admittedly probably outdated experience with the brand in friends' systems and in showrooms.