Vavles will produce a purer sound that transistors. If only our cameras were built like that.. A bit heavy, but still.
Miss those old radios.
Heres a little snippet about valve..
"Engineering techniques invariably involve making compromises, eg. presence of HUM against overall ease of manufacturing, so that at home one can take extra steps to maximize hum rejection in otherwise well-built amplifiers. By observing every possible "injection" mechanism and making efforts to minimize each one can the overall hum index of a tube amp be brought down to nil. What follows is a synopsis of the work I do to tube amps to eliminate the hum without resorting to costly DC filament supply blocks."
Full readings about these baby's here :
http://www.lynx.bc.ca/~jc/hum.html
I think most hum comes from our own hears after a concert !.
Theo.