erik -> thanks for your feedback. In my case it is between 8-15 minutes during warm-up and then it goes away. Still not sure if this is related to pin-socket contact or not.
I have exactly the same feeling about it as you - I do not want to send them back, these are really hard to get and I love the sound and built quality...
Jonesy -> again, accept my big thank you for your help. I tried to follow all you advices, cleaned the pins as good as it was possible and this is the result (see the image). Haven't tried it out yet...
Ralph -> so you say it is the tube itself? I thought microphonics is cause by mechanical vibration, not a kind of self-resonance... Might be that I am wrong... Does this mean the tube is faulty then?
