I'm planning to build a single double triode vacuum tube as I have seen many schematics even though most of them are low voltage (20-40v). However I didn't seem to find a high voltage single double triode schematic. I know that double triode can be (and was made that way to do it) used for 2 audio signals. (one triode amplifies one signal only)
To keep it simple, would this schematic be appropriate (and have good results) for a headphone amp. Filters will be recalculated so don't mind little things in the schematic. The tube I am planning to use is ECC85 (very similar to 12AT7).
And.. would it amplify the sound without distortion? ( in some cases preamplifier acts more like de-amplifier (lowers the signal) when things are not 'balanced' )
EDIT: I've got an idea. What if I output the sound from triode to an op-amp? (OPA2134) Would this work instead of putting a transformer to drive headphones?