^ http://www.zenn.com.sg/DHT%20preamps.htm
"The reason for the scarcity of such designs is the problem of noise which is difficult to overcome in using a direct heated triode as a preamp stage."
I think he is primarily concerned with filament supply noise. Aside from the rather vague info on that page that preamp seems a bit scarce itself. Is there another page somewhere with more info? Couldn't find anything on the zenn web site. I do like the guy's article about damping small signal tubes in oil. Buddha and I talked about doing that years ago, but never followed through with the idea.
