Apparently there is a potential fix for mario bros sound which you perform the following:
Change
#define OLD_SOUND (1)
to
#define OLD_SOUND (0)
in mame/include/mario.h and get netlist mario sound.
Anyone know how to do this? Enable netlist sound? I found put the mame/include folder with mario.h in my mame folder and put the mario.c into audio. no dice. want to try this out...