Alsa probably is fine, since you do get some sound.
However, if you have a mixer like mine
, you can have like 100 wrong settings. Also, keep in mind that some things multiply eachother, so if you set master to 50% and PCM to 50%, only 25% of PCM will come through, which might not be loud enough to be heard. The low sounds could come from the LFE channel, you might want to increase the "Side" settings (if you have 'm), and Front too.