Imac 27" mid-2011 running Maverics 10.9.3* I'm not getting any sound from internal or ext. speakers.* I can hear the startup sound when booting up. System Preferences->Sound only shows Digital Out for OUTPUT and Output Volume is maxed and can't be adjusted.* Mute is NOT checked. I've done an SMC and PRAM reset with no change.* I've tried multiple times plugging and unplugging the external speaker cable jack. Any suggestions would be most welcome.