Hi Geert
This is a bug in our release on Snow Leopard, it works fine on Leopard and Tiger. We're using an old part of the API, the one from Tiger, which is supposed to work in Snow Leopard but seems to have problems. We're working on it right now and a fix should be in our next bugfix stable release, hopefully this week.
In the meantime, changes in sample rate away from 48K will cause problems, not because the sample rate is different (our system is well tested at other sample rates) but because the notification from MacOS that the change occurred seems to be doing something strange. Sorry about this, we'll fix it as soon as we can.
John