Hello all. I've recently upgraded my OS. I always wait a good 4 or 6 months after the latest version is launched to make sure that all updates will be in working order with the software in use. Unfortunately this caution didn't quite work this time, as the sound settings wouldn't recognise the sound card that has been attached to the computer since I purchased it. I am beyond disappointed. When I invested in Mac, the point was essentially to have a more efficient machine to work with music, now the whole purpose is defeated with an OS that simply can't detect the sound device. Reading thoroughly among some forums I noticed that this was an issue addressed in a large number of times by Mac users, with no satisfactory from admins other than, contact the manufacturer of the software. Will all due respect I doubt that Line 6 or any of the Midi creators have any responsibility here, as the upgrade in OS has been launched by Apple. I suppose I have no choice but backing up all data and simply try to restore to factory settings, but I'd like to discourage anyone to even look at this Sierra, at least if they ever have the intention of plugging their guitars in the Mac Book. I've been an Apple user for a long time, and now I feel beyond let down. Very, very disappointing people.