Hi Manike - Not sure - may be a combination of both. I’m thinking it could be an issue with the clock rate changing and something getting out of sync between a DAW, the Mac, AXR4 2TR PC outputs, and the AXR4U. I typically run at 48khz. It is unpredictable as to when the kernel panic occurs, but I do send a report to Apple every time it happens. I’m using the AXR4U full time again to see if it happens now that I’m running Big Sur 11.6. Hoping there is also a driver/firmware update that adds 32bit back for Mac users. As soon as I switched back from my Presonus Quantum interface to the AXR4U, I did notice the sound quality difference with the AXR4U which is awesome!