Tommy Emmanuel apparently learned by transrcibing, famously thinking that both the bass line and guitar lines he was hearing were a singular "guitar part". Just by having his expectations (incorrectly) raised, he rose to the occasion and played both parts.
I forget where I heard this story -- it's probably either rather famous, or buried in an interview somewhere.
I forget where I heard this story -- it's probably either rather famous, or buried in an interview somewhere.