No headphone sound on 27' imac 12,2

[El_Gigantor]

Someone please help.

No matter what Linux Distro I use, i can't get any sound out of my external speakers plugged into my headphone jack. i get sound out of the internal speakers even when i select the headphone jack. I've tried unmuting the "front speaker" and "surround" but still nothing. i have also tried adding "options snd-hda-intel model=imac27" and "options snd-hda-intel index=0 model=imac27"to the end of alsa-base.conf with no change. any ideas?????