The output transistor is class-A that wastes a lot of battery power all the time even when there is no sound, use a class-AB complementary output stage instead.
You should NEVER put DC through an earphone transducer which might burn it out or cause its membrane to be pushed to one side, use a coupling capacitor to feed it AC.
You do not have a condenser mic that needs a 48V supply, instead you have an electret mic that has the 48V built into its electret material and has a Jfet to reduce its output impedance.
The preamp transistors are biased wrong so they do not work. You do not need three transistors to make a simple mic preamp, two transistors biased correctly are fine like this: