Small improvement with Dolby Atmos, but it's a dynamic improvement, therefore variable.
What I mean is that do not expect to be able to have a fix 10 dB gain for example, and sound is still not as high, clear and crisp as on iPod / iPhone for exemple
Did not try the phone ear speaker, only earphone.
I tried every tutorial relative to mixer_paths.xml, but no improvement so far
Maybe someone someday will find a kernel / system fix to that !