Applies to: Clarett Range, Red Range
UPDATE (3rd October 2016):
We have a build of our Thunderbolt driver which we believe alleviates the problem with glitchy audio present on iMac 17,1 systems - this build fixes the problem with playback at all sample rates, however on some systems there have been reports of occasional clicks/pops when recording. If you have a Clarett interface and the affected model of iMac please Contact Support who will be able to send this out for you to try.
We have been doing all that we can to find a resolution since learning about the problem and are continuing to do so. Unfortunately, since the issue occurs only on one very specific system and only occurred after an update to OS X, we have requested assistance from Apple and are liaising with them to find a permanent solution. We will update this article and any customers who have previously raised this issue with our support team as soon as possible.
We have recently been made aware of some problems with Clarett interfaces when used in conjunction with the latest update to El Capitan (version 10.11.5) and later (including macOS Sierra) and a particular iMac Model (Model Identifier: iMac 17,1. iMac Retina 5K, 27-inch, Mid or Late 2015).
NOTE: It appears that once a system has been updated to 10.11.5, reverting to an older version of the OS from a backup does NOT appear to rectify the problem.
If you're unsure which specific Mac model you have, you can find this information by clicking the Apple Logo in the top left corner of the screen, then going to About This Mac > System Report. The 'Model Identifier' appears in the Hardware tab.
This issue tends to affect all sample rates above 44.1kHz, but you should get clear audio when playing back and recording using 44.1kHz.
We are discussing this issue with Apple as a matter of priority with a view to finding a solution as soon as possible. As soon as we have more information on this matter we will update this article.