Essentially not responding to the knob turning. And like you said, it happens after my PC goes to sleep and a restart of the system is all it needs.

Yeah, good company. I have an issue with mine where sometimes it goes unresponsive as I run it 24/7. They shipped me a replacement with no questions asked and before I even sent my original back, but the replacement still does it but just at way less frequency.

Otherwise it makes switching between my headphones and speakers a damn breeze.