|100uv signal will drive the earbud.|
|1mv signal produces 400ua which is half the ear bubs max rating.|
|10 mv is near 4ma drive which is enough to burn out my earbud.|
This amp will require some limiting to keep from damaging my earbud.
What if the output stage used 2 mosfets? I have the 2 -200Ohm resistors limiting the output stage current. I tested the circuit without the 200 Ohm resistors and it produced 20 ma signal. That may be another project.