emumix_get_volume
emumix_set_volume(sc->card, M_FX0_REC_L, emumix_get_volume(sc->card, M_FX0_FRONT_L));
emumix_set_volume(sc->card, M_FX1_REC_R, emumix_get_volume(sc->card, M_FX1_FRONT_R));
new_vol = emumix_get_volume(sc, mixer_id);
int emumix_get_volume(struct emu_sc_info *sc, int mixer_idx);