JohnDuncan:Market size, primarily. EBRicky said elsewhere that he'd sold something like 90 pairs of his five-star, reasonably affordable, mainstream product. What does that mean for headphone amps? Ten a year for any given model? I wouldn't fancy my chances, no matter how good I could make something.
Sorry John but who is EBRicky?
I know what you're saying as far as sales....but I wouldn't be expecting to jack in the day job.