hi Damir
thanks i think that i first build it with the ec8010
i will drive the ec8010 at 20 ma
and use a gridchoke on the 300b the same as you use
just for trying try a 10k resistor parallel with the gridchoke
and report the sound on this forum
i find this better sounding i have various transformers laying around
also chokes so i can try different things
as you say expect large input capacitance with the ec8010
what does this mean???
give this some roll of in hi or low frequencies?
and is there a solution
i use no active preamp just a 24 steps autoformer with 8 feet
(2 meters)interlink between the autoformer and the amp