> very good speakers

All of the above is true but this, actually, is not entirely: they use a lot of DSP. If you try the same speakers with regular Fedora Asahi with no DSP profile (i.e. vanilla sound), they're very mediocre and do not handle bass well. So, like with many aspects of Apple hardware, this is an example of their software/firmware complimenting the hardware.

It's part DSP, part thermal modeling. The speakers can be driven pretty hard, but will overheat and fail if too much energy is put into them in too short a time. macOS has a thermal model to keep the speakers within safe limits; a major component of Asahi's DSP profile is a similar model. (Without that model in place, Asahi reduces the peak power level to avoid damage.)