Dear Quinn, In the Big Sur 11.3 beta 2 release, there are some strange development changes in CoreAudio causing instability of plug-ins. I spent so far 2 days trying to discover what's changed or what I shall change but it behaves quite unstable and every time I start to believe that I found the root cause, it dies somewhere else... There are console records like: default 15:06:27.793116+0100 coreaudiod HALS_DefaultDeviceManager::PickDefaultDevice: 'sOut' | picking 56: 'BuiltInSpeakerDevice'/'ispk' default 15:06:27.793167+0100 coreaudiod HALS_DefaultDeviceManager::PickDefaultDevice: 'sOut' default 15:06:27.793245+0100 coreaudiod HALS_DefaultDeviceManager::UpdateDefaultDevice: 'sOut' default 15:06:27.793322+0100 coreaudiod HALS_DefaultDeviceManager::CheckForChanges: 'sOut' default 15:06:27.793399+0100 coreaudiod default 15:06:27.793462+0100 coreaudiod HALS_DefaultDeviceManager::CheckForChanges: 'shrd' default 15:06:27.793533+0100 coreaudiod HALS_DefaultDeviceManager::UpdateDefaultDevice: 'shrd' default 15:06:27.793611+0100 coreaudiod HALS_DefaultDeviceManager::FindPreferredDefaultDevice: 'shrd' default 15:06:27.793751+0100 coreaudiod HALS_DefaultDeviceManager::FindPreferredDefaultDevice: 'shrd' default 15:06:27.793828+0100 coreaudiod HALS_DefaultDeviceManager::PickDefaultDevice: 'shrd' default 15:06:27.794164+0100 coreaudiod Heap has 1 items or... default 15:06:27.904949+0100 coreaudiod HALC_ShellDevice::_InitializeDriverPlugIn: *X*X*X Not loading the driver plug-in into coreaudiod default 15:06:28.802160+0100 SpeakerAmp HALC_ProxyIOContext::_StopIOProc: IOProc doesn't exist crash: Sending event: com.apple.stability.crash {"appVersion":"1.0","exceptionType":1,"incidentID":"3C3C7C9D-1805-4CE3-99DD-05951DF935CA","logwritten":1,"process":"com.apple.audio.Core-Audio-Driver-Service","responsibleApp":"coreaudiod"} errors like: HALC_ProxySystem::GetObjectInfo: got an error from the server, Error: 560947818 (!obj) etc... Could you please confirm that there is an ongoing development in that API and that there will be further update prior 11.3 release? I found no info in the RNs. I am wondering whether I shall keep searching what's happened now before customers start complaining about it or whether it is wise to wait for a next more stable build. Thank you in advance. Pavel