Hi Guys, I am trying to add and test an LFX APO with a UAA-compliant USB device. We have verified this same APO with a UAA-compliant HD Audio device thanks to the DDK example. For now, I am using a pair of HP USB speakers which uses the "(Generic USB Audio)" driver. The reason I am using the generic driver is we need to support and describe the inf setup for the APO on a USB device to the OEM; however, the OEM's driver is not yet ready. So, I tried modifying the inf file from the HD Audio example in the DDK to use USB Audio instead. When I update the driver, it looks promising, however at the very end it denies loading it, citing a generic error: "Windows found driver software for your device but encountered and error while attempting to install it." "The class installer has denied the request to install or upgrade this device." Obviously, it could be any number of things. However, I was wondering: 1) Are there important differences I probably overlooked when making this change from HD Audio to USB Audio? 2) Is it possible what I am trying to do is not permitted (on the Generic USB Audio driver)? 3) Can you identify a way I can get more information about the error or preparing an APO for UAA-compliant USB Audio devices? Thanks so much for all your support! Regards, Ally