Design a class AB audio amplifier
For 10 watts into 8 ohm speaker, you can do this system design

P = Vrms * Vrms / Rload

10 watts = V * V / 8

10 * 8 = V * V thus Vrms_out ~~ 9 volts RMS, or 2.828 * 9 peakPead


You will need headroom. So have at least 40 volts VDD.
Now for the gain:
The topology of common_emitter amplifier, into a resistive load, has maximum voltage gain of VDD / 0.026; with 40 volts  / 0.026 (or 40 * 39) , the maximum gain is nearly 1,600. You only need 9_rms/0.5_rms or 18X.
Now for the load on the collector. That is heavy. Many milliAmps, because of 1 amp+ Iout, and moderate beta of the two output transistors.  One amp / Beta = 100 ==&gt; Ibase of 0.010 amp = 10mA.
What to do? The base currents will tend to cancel, so assume 10mA (net) into the two output transistors. And assume another 10mA to provide pullup to the +40 volts. So plan to operate that first transistor at 0.020 amps.
WIth 20mA Icollector and 40 volts, the maximum power dissipation of your first transistor (that common emitter) will be 20mA/2 * 40 volts/2 (for passive loads), or 10mA * 20Volt = 0.2 watts.
So you need a transistor in the voltage amplifier (gain of 9/0.5 = 18x) able to
dissipate 0.2 watts. Probabaly don't worry about that yet.
How to design that first (voltage gain) stage?