Im sure you have all read this but as a dht triode user its got some nice references...
http://nutshellhifi.com/library/tinyhistory1.html
Nutshell hifi
#1 Nutshell hifi
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number