How does an speaker amplifier have to be build for a given DAC output signal?
Google "LM386" and take one of the examples in the datasheet:



With the default 20x gain you will probably need ~ 1:40 attenuation between the DAC output and the LM386 input. Use a log potentiometer for the 10k to set the attenuation, once you know the correct setting you can swap it for two resistors.