I'm assuming its set up as a massive cathode follower and the bank of capacitors are the output coupling arrangement. Still may be wrong but thats all I got.Even transformer-less, seems a bit of a stretch for a headphone amp unless you're running hardcore electrostatics ...
Not if it had 24 bias pots.Does it require a matched quattuorvigintuple of tubes?
6j1's they are common in the chi-fi stuff tube buffers, headphone amps normally two not 24 tubes though.Do you know what are the tubes?
The right low power tubes must work for OTL , & makes sense!