Kronzilla or for that matter any of KR Audio's tube amps out of Prague has been my favourite for years(currently got 3 pcs.). Build quality and sound is our of this world. May not be the prettiest around but they do for sure stand out in every other aspect.
Highest BUILD quality tube amps?
Not so much with sound...lots of ways to fine tune thru tube rolling, etc. I'm just curious which tube amps are built to last for many years with the least amount of repairs. I know Mcintosh comes to mind for longevity. I was snooping around on the web and Air Tight seems to be built like a tank and I've never read any poor repair histories. Luxman same thing. Any others come to mind?