au_set_gain
static int au_set_gain(struct audio_softc *, struct au_mixer_ports *, int, int);
error = au_set_gain(sc, &sc->sc_outports, pgain, pbalance);
error = au_set_gain(sc, &sc->sc_inports, rgain, rbalance);
au_set_gain(sc, &sc->sc_outports, newgain, balance);
au_set_gain(sc, &sc->sc_outports, newgain, balance);
au_set_gain(sc, &sc->sc_outports, newgain, balance);