if (!spec->adc_nids && spec->input_mux) {
                /* check whether NID 0x07 is valid */
                unsigned int wcap = get_wcaps(codec, 0x07);
+               int i;
 
                /* get type */
                wcap = (wcap & AC_WCAP_TYPE) >> AC_WCAP_TYPE_SHIFT;
                        spec->num_mixers++;
                }
                spec->capsrc_nids = alc268_capsrc_nids;
+               /* set default input source */
+               for (i = 0; i < spec->num_adc_nids; i++)
+                       snd_hda_codec_write_cache(codec, alc268_capsrc_nids[i],
+                               0, AC_VERB_SET_CONNECT_SEL,
+                               spec->input_mux->items[0].index);
        }
 
        spec->vmaster_nid = 0x02;