Strange problem w/MR816x and Silverlight

It’s probably something I have done somewhere, but I just can’t figure it out… I have set the WDM output routing to outputs 1&2 in the MR Editor, and this works as expected for everything EXCEPT when I view some kind of Silverlight web content, e.g. the tutorials at

Silverlight audio appears at outputs 3&4. And if I change my WDM settings to route WDM output to 3&4, then Silverlight audio goes to 5&6. Always the next output pair relative to what I’ve selected. This drives me nuts. Any ideas as to where I can have screwed this up, anyone? :confused: