I'm trying to fix an issue with our AvStream UAC2 Driver concerning data formats In the Windows 8.1 "Sound->Line Out Properties->Advanced Tab->default Format" dropdown there are formats not supported by our device and furthermore not in ANY of our dataranges! The dataranges for the device are populated correctly and all formats other than the ones our hardware supports are correctly rejected by our Intersect and SetProposedDataFormat handlers. If I select one of the unsupported formats from the dropdown, and hit apply, it is correctly rejected by the device and a "Format not supported by the device." messagebox is displayed. Does anyone know how that list is actually populated???? I want it to only show the formats actually supported by our device. I've seen similar posts concerning dynamic format changes but this seems to be a different issue... Also, is there a way to monitor the actual property request IRPs being sent to the pin? I've used KSStudio, but it doesn't seem to be able to show this (mmsyscpl queries). Thanks!