Hi
Here a photo off my last creation, it's a otl head-amp that use one 6AS7G tube for each cannel, "not only one half". Most of the manufactures believe that one half of a 6AS7G is enough, to drive a headphone in a proper way, They are wrong. I have been building with tubes since the early eighties, so I know how to build a tube-amp.
Best regards
Torben
