A lot of hardware audio interfaces were usb2 which demands cpu time as the system has to poll the usb device rather than act on an interrupt. This caused very low latencies to basically never work without dropouts. I can distinguish a 20-30ms latency and above that it becomes too difficult to ply anything meaningful. Even my semi-pro tascam interface could only sample between 11-14ms. Faster cpus over the last 5 years and ultimately Usb3 solved the polling problem but is just now picking up traction in newer devices due to the usb-c connector.

Interesting, I thought in general polling was lower-latency at the cost of higher CPU utilization. But maybe its not really true for USB.

The complaint about CPU time is interesting—surely the whole point is that you want to spend CPU time more often? Then again, it’s been a long time (15 years?) since I’ve seen dropouts, and I’m definitely using USB2 (not USB3) and low buffer sizes (more like 10-15ms, not 20-30ms).