In older versions, volume was set using the soundVolume setting, where 0=1x, 1=2x, 2=3x, and 3=4x. Currently, the soundVolume setting takes a range from 0-200, with 0=0% and 200=200%, however, the default value in trunk/src/sdl/vbam.config-example is set to 0, muting the volume.
vbam.cfg incorrect volume setting
vbam.cfg incorrect volume setting
Should be ok now. Thanks for the report.