eGPU + USB Audio dropouts

[elanf]

Mac Mini late 2018
eGPU: BlackMagic eGPU Pro
Version: 10.14.5 (but also tried in beta 10.15)
DAC: Tried various, but mostly Cambridge Audio DACMagic 100

When the eGPU is being used, the USB sound engine is reset every few minutes, resulting in an audio dropout. Example logs:

default 09:01:46.518108 -1000 kernel USB Sound assertion (Resetting engine due to error returned in Write Handler) in /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleUSBAudio/AppleUSBAudio-315.6/AppleUSBAudioDevice.cpp at line 6520
default 09:03:06.124181 -1000 kernel USB Sound assertion (Frame Difference is greated than expected) in /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleUSBAudio/AppleUSBAudio-315.6/AppleUSBAudioStream.cpp at line 5208
default 09:03:06.321054 -1000 kernel USB Sound assertion (Resetting engine due to error returned in Write Handler) in /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleUSBAudio/AppleUSBAudio-315.6/AppleUSBAudioDevice.cpp at line 6520
default 09:03:06.321067 -1000 kernel USB Sound assertion (Resetting engine due to error returned to Feedback) in /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleUSBAudio/AppleUSBAudio-315.6/AppleUSBAudioDevice.cpp at line 6528

I've tried different USB cables, different USB ports, and plugging the USB DAC into:

- Internal USB port.
- eGPU USB port.
- Totally separate MiniDock's USB on separate Thunderbolt bus.

None of this seems to make a difference.

 

[dia3olik]

Try extracting audio from DP or HDMI...this way it should be totally fine and also more in sync to the image if extracted from the monitor audio out.

 

[elanf]

Thanks for the reply! In this case I'm just looking for high quality audio, not synced with any video. But maybe something like https://www.amazon.com/Extractor-Aerctor-Optical-Splitter-Converter/dp/B07BSKT1VD would work if I just want to avoid the USB bus entirely.

 

[dia3olik]

exactly! I suggested this to bypass the bus and you can even control the volume with some utilities (MacOSX sees it as fixed volume by default)