X usually means crystals, but that sure doesn't look like an smd crystal to me, and more like a normal capacitor. If you can get hold of a capacitance meter you could measure the one on top and take a look. It's connected to pin 6 of the 386d which is V+ and a big plane which looks like ground, so it's most probably a bypass cap. The failure is most probably a short in "X12" causing the blown up. C30 is also possible but not so likely since it has R25 in series. You might also want to check the via near C30, and also output pin 5 of the 386d to V+ and ground in case the amp is shorted. Check also C29 since electrolytic caps are prone to aging.

C30 should be 47nF and X12 probably decoupling capacitor 47-100nF. Page 15-16.

Thank you for your answers.
Maybe the best thing to do is to desolder C28 and X11 to mesure their capacities.

You could but I don't think that is necessary now that we have the schematic. Card manufacturers usually just follow the reference design from the datasheet. Other components on your card match those in the datasheet so it is quite certain that they just copy the reference design.

I have done the schematic around the 386, following the tracks.
According to the datasheet, X12 is 100nF and C30 is 47nF, so you were right.
Thank you all. I will try to replace blown components with these values.