Core Audio Issues:
It seems the crackles are manifesting at a low level in Core Audio. We are testing a few external DACs that exhibit this even without DPS. Crackles seem to be related to devices that do not use the default Apple audio drivers. There seems to be some “drift” where the digital clock becomes out of sync over time.
According to our Pro Audio expert, Phil Fuller, El Cap has been notorious for poor support of third party audio drivers. I’m really hoping we are not entering Mavericks territory! Some of you may recall it was impossible to resolve some of the Mavs issues. It wasn’t until the release of Yosemite the issues were resolved. We didn’t have to do anything as the problems reside deep inside Core Audio and we do not have access to that code.
We will all be keeping our eye on the Core Audio issues.
Regarding switching modes:
The behavior is DPS saves the last mode you were using at the time the app quits (computer shutdown). So, instead of detecting the headphone jack on launch, it is simply recalling the last mode used.
We can make the behavior better by first recalling the last used mode then polling the headphone jack and following the user’s preference. I’ll add it to our issue list.
Regarding numbers showing up in the Output Device list:
We are aware of this and are looking into the solution. It seems to only happen during update so we will focus our attention to that case. It is only the label that is affected and selecting the output resolves the issue.