I made a bootable backup of my Macbook Pro using Carbon Copy Cloner to a USB hard drive. I am intending to clone back from the USB hard drive to a Macbook Air 13" 2010. But first I tried booting up from the drive on the MBA. Everything is fine, except -- there is no sound!! It's not a problem with the machine itself, if I boot natively the sound works fine. I should note that I did install the volume booster app 'Boom'. I tried uninstalling this and restarting but it still shows up in the list of sound devices. Any advice or recommendations?