I see that he wants a mic preamp and not a headphones amp.
There are many microphone preamp circuits online. Some are written by school kids and are also full of errors.

 

Two LM386 DIY kits will do entry level stereo. When the volume is low, the distortion is sufficiently low to pre-amplify into
a tone control board like NE5532. Instead of going with all the hype just making these perform should give more incentive to build even better quality but you might find these can be quite impressive.

 

Sorry, MaxMichaels, I see that you did not copy this headphones amplifier, instead it was recommended by Dodgydave who might be a student who did not look at the datasheet.

That was cold-blooded.