@luz I've repeat all the mentioned steps and it works now... I can't belive
My fault was that I wasn't applying 210-omega2-sound-max98357a.diff correctly. The patch fails for 0.3.2 b238, and I wasn't applying it correctly (doing changes manually)
I've tested using mpg123 mp3 player and aplay commands. Works fine.
Also thank you for the tip about mixer and hxcmodplayer