Btw, just to let you guys know, I finally built the headphone amp. As I use Bayerdynamic DT-990 Pros with 250 ohm impedance, I decided to try ECC82 white cathode follower as output stage. To get a bit more current swing, I upped B+ to 300 volts, and because of that I switched the input tube to ECC40 (which I had on hand anyways, so no need to spend $$).
The most complicated part of the whole project was that I had decided to use SMPS to generate both the heater voltage and B+. MAX1771 chip I used for B+ is a bit crappy (in retrospect I should have used LM3478 instead), and there were some issues to be solved before I managed to get the amp to be quiet enough, but now it seems to work well enough.
The most complicated part of the whole project was that I had decided to use SMPS to generate both the heater voltage and B+. MAX1771 chip I used for B+ is a bit crappy (in retrospect I should have used LM3478 instead), and there were some issues to be solved before I managed to get the amp to be quiet enough, but now it seems to work well enough.