ES_1371_GPIO_OUT
if (ensoniq->ctrl & ES_1371_GPIO_OUT(4))
ensoniq->ctrl |= ES_1371_GPIO_OUT(4); /* switch line-in -> rear out */
ensoniq->ctrl &= ~ES_1371_GPIO_OUT(4);
ensoniq->ctrl |= ES_1371_GPIO_OUT(1); /* turn amplifier on */