Hi there, After upgrading to 10.10.2 from 10.10.1 I now have no sound at all. I upgraded using the correct 10.10.2 installer, (for 10.10.1) from the Apple site. I then repaired permissions and rebooted - still no audio. I then downloaded the appropriate 10.10.2 combo from the Apple site and did an install, my iMac then did a restart, and still no audio. The startup chime is loud and clear and the volume control is turned up. Any ideas anyone? All help is gratefully received. John. Fixed! BoomDevice was the culprit and in System Preferences/Sound/Output for some reason BoomDevice had become the default setting and not Internal Speakers ... Although deleting BD completely is proving a little tiresome, it still appears in the list of devices in the Output and Input windows in System Preferences/Sound after being deleted from the system! Thank you guys for your replies, always appreciated!