When measuring the output of ASIO401 a4144b7 (default settings) playing a sweep with an oscilloscope, this is how the beginning of the stream looks like:

The first ~20 ms (which, perhaps coincidentally, is about the size of the QA401 hardware queue) is distorted.

This doesn't seem related to something happening in the previous stream as I can reproduce it even when the previous stream was just a bunch of silence.