LM386N-1 I used before worked well, but has some disadvantages. There was a hearable distortion in the sound and I needed more amplification to create the required loudness.
I found the TDA 7052 chip, which was formerly produced by Philips, but now by NXP semiconductors. It contains everything required for an amplifier. You just have to supply power, the input signal and there are two outputs to connect the 8Ω speaker.
The updated schema looks like this:
I also added a trimmer to adjust the volume of the output. The value of the trimmer is missing in the schema. I used a 47kΩ trimmer, but a 10kΩ trimmer will work fine as well.