For me this input stage of an old tape machine is one of the biggest mistery .Is there any particular reason for why Nakamichi engineers chose a self biased ccs here or is the carefull dc vs ac gain that really matters here? I don't think i've seen this type of ccs in more than two ore maybe three comercial machines, while i don't really remember the other two.Could somebody make a in debth technical assesement of this stage? The sound of that thing is magical and i think that this input stage has its merits allthough i met other tape machines that sound really well using op-amps or differential fet input and op-amps but identical dolby section...
