Hi Ruslan, thanks for all your efforts to make the USB Audio Gadget work in Win10 using UAC2. Meanwhile I managed to apply and compile your previous modifications and now my Raspberry PI shows up in the Windows Device Manager as a valid UAC2 audio device. Unfortunately it still doesn't work to transfer any audio as it seems the audio endpoints or the topology is not working. I checked it with some tools and found one providing some information on the USB part (it's called UVCview.exe and is part of the Windows Driver Kit). Here's the output which I hope can give some hints on the problems still existing in this driver: ---===>Device Information<===--- English product name: "Linux USB Audio Gadget" ConnectionStatus: Current Config Value: 0x01 -> Device Bus Speed: High Device Address: 0x0F Open Pipes: 0 *!*ERROR: No open pipes! ===>Device Descriptor<=== bLength: 0x12 bDescriptorType: 0x01 bcdUSB: 0x0200 bDeviceClass: 0xEF -> This is a Multi-interface Function Code Device bDeviceSubClass: 0x02 -> This is the Common Class Sub Class bDeviceProtocol: 0x01 -> This is the Interface Association Descriptor protocol bMaxPacketSize0: 0x40 = (64) Bytes idVendor: 0x1D6B = The Linux Foundation idProduct: 0x0101 bcdDevice: 0x0510 iManufacturer: 0x01 English (United States) "Linux 5.10.17-v7l-R3LAY_TEST+ with fe980000.usb" iProduct: 0x02 English (United States) "Linux USB Audio Gadget" iSerialNumber: 0x00 bNumConfigurations: 0x01 ===>Configuration Descriptor<=== bLength: 0x09 bDescriptorType: 0x02 wTotalLength: 0x00E2 -> Validated bNumInterfaces: 0x03 bConfigurationValue: 0x01 iConfiguration: 0x00 bmAttributes: 0xC0 -> Bus Powered MaxPower: 0x01 = 2 mA ===>IAD Descriptor<=== bLength: 0x08 bDescriptorType: 0x0B bFirstInterface: 0x00 bInterfaceCount: 0x03 bFunctionClass: 0x01 -> Audio Interface Class bFunctionSubClass: 0x00 *!*CAUTION: This appears to be an invalid bFunctionSubClass bFunctionProtocol: 0x20 iFunction: 0x04 English (United States) "R3lay PI" ===>Interface Descriptor<=== bLength: 0x09 bDescriptorType: 0x04 bInterfaceNumber: 0x00 bAlternateSetting: 0x00 bNumEndpoints: 0x00 bInterfaceClass: 0x01 -> Audio Interface Class bInterfaceSubClass: 0x01 -> Audio Control Interface SubClass bInterfaceProtocol: 0x20 CAUTION: This may be an invalid bInterfaceProtocol iInterface: 0x05 English (United States) "Topology Control" ===>Audio Control Interface Header Descriptor<=== bLength: 0x09 bDescriptorType: 0x24 bDescriptorSubtype: 0x01 bcdADC: 0x0200 wTotalLength: 0x5308 bInCollection: 0x00 ===>Descriptor Hex Dump<=== bLength: 0x08 bDescriptorType: 0x24 08 24 0A 06 01 01 00 06 ===>Descriptor Hex Dump<=== bLength: 0x08 bDescriptorType: 0x24 08 24 0A 05 01 01 00 07 ===>Descriptor Hex Dump<=== bLength: 0x11 bDescriptorType: 0x24 11 24 02 01 01 01 00 05 02 03 00 00 00 00 03 00 08 ===>Descriptor Hex Dump<=== bLength: 0x11 bDescriptorType: 0x24 11 24 02 02 00 02 00 06 02 03 00 00 00 00 03 00 09 ===>Descriptor Hex Dump<=== bLength: 0x0C bDescriptorType: 0x24 0C 24 03 04 01 01 00 02 06 03 00 0A ===>Descriptor Hex Dump<=== bLength: 0x0C bDescriptorType: 0x24 0C 24 03 03 00 03 00 01 05 03 00 0B ===>Interface Descriptor<=== bLength: 0x09 bDescriptorType: 0x04 bInterfaceNumber: 0x01 bAlternateSetting: 0x00 bNumEndpoints: 0x00 bInterfaceClass: 0x01 -> Audio Interface Class bInterfaceSubClass: 0x02 -> Audio Streaming Interface SubClass bInterfaceProtocol: 0x20 CAUTION: This may be an invalid bInterfaceProtocol iInterface: 0x0C English (United States) "Playback Inactive" ===>Interface Descriptor<=== bLength: 0x09 bDescriptorType: 0x04 bInterfaceNumber: 0x01 bAlternateSetting: 0x01 bNumEndpoints: 0x02 bInterfaceClass: 0x01 -> Audio Interface Class bInterfaceSubClass: 0x02 -> Audio Streaming Interface SubClass bInterfaceProtocol: 0x20 CAUTION: This may be an invalid bInterfaceProtocol iInterface: 0x0D English (United States) "Playback Active" ===>Descriptor Hex Dump<=== bLength: 0x10 bDescriptorType: 0x24 10 24 01 01 00 01 01 00 00 00 02 03 00 00 00 00 ===>Audio Streaming Format Type Descriptor<=== bLength: 0x06 bDescriptorType: 0x24 bDescriptorSubtype: 0x02 bFormatType: 0x01 bNrChannels: 0x02 bSubframeSize: 0x10 bBitResolution: 0x07 bSamFreqType: 0x05 tSamFreq[1]: 0x380501 (3671297 Hz) tSamFreq[2]: 0x080401 (525313 Hz) tSamFreq[3]: 0x000125 (293 Hz) tSamFreq[4]: 0x000000 (0 Hz) tSamFreq[5]: 0x050700 (329472 Hz) ===>Endpoint Descriptor<=== bLength: 0x07 bDescriptorType: 0x05 bEndpointAddress: 0x01 -> Direction: OUT - EndpointID: 1 bmAttributes: 0x05 -> Isochronous Transfer Type Synchronization Type = Asynchronous Bulk Transfer Type wMaxPacketSize: 0x0138 = 1 transactions per microframe, 0x138 max bytes bInterval: 0x04 ===>Descriptor Hex Dump<=== bLength: 0x08 bDescriptorType: 0x25 08 25 01 00 00 00 00 00 ===>Endpoint Descriptor<=== bLength: 0x07 bDescriptorType: 0x05 bEndpointAddress: 0x81 -> Direction: IN - EndpointID: 1 bmAttributes: 0x11 -> Isochronous Transfer Type Synchronization Type = No Synchronization Bulk Transfer Type wMaxPacketSize: 0x0004 = 1 transactions per microframe, 0x04 max bytes bInterval: 0x04 ===>Interface Descriptor<=== bLength: 0x09 bDescriptorType: 0x04 bInterfaceNumber: 0x02 bAlternateSetting: 0x00 bNumEndpoints: 0x00 bInterfaceClass: 0x01 -> Audio Interface Class bInterfaceSubClass: 0x02 -> Audio Streaming Interface SubClass bInterfaceProtocol: 0x20 CAUTION: This may be an invalid bInterfaceProtocol iInterface: 0x0E English (United States) "Capture Inactive" ===>Interface Descriptor<=== bLength: 0x09 bDescriptorType: 0x04 bInterfaceNumber: 0x02 bAlternateSetting: 0x01 bNumEndpoints: 0x01 bInterfaceClass: 0x01 -> Audio Interface Class bInterfaceSubClass: 0x02 -> Audio Streaming Interface SubClass bInterfaceProtocol: 0x20 CAUTION: This may be an invalid bInterfaceProtocol iInterface: 0x0F English (United States) "Capture Active" ===>Descriptor Hex Dump<=== bLength: 0x10 bDescriptorType: 0x24 10 24 01 04 00 01 01 00 00 00 02 03 00 00 00 00 ===>Audio Streaming Format Type Descriptor<=== bLength: 0x06 bDescriptorType: 0x24 bDescriptorSubtype: 0x02 bFormatType: 0x01 bNrChannels: 0x02 bSubframeSize: 0x10 bBitResolution: 0x07 bSamFreqType: 0x05 tSamFreq[1]: 0xC40582 (12846466 Hz) tSamFreq[2]: 0x080400 (525312 Hz) tSamFreq[3]: 0x000125 (293 Hz) tSamFreq[4]: 0x000000 (0 Hz) tSamFreq[5]: 0x000000 (0 Hz) ===>Endpoint Descriptor<=== bLength: 0x07 bDescriptorType: 0x05 bEndpointAddress: 0x82 -> Direction: IN - EndpointID: 2 bmAttributes: 0x05 -> Isochronous Transfer Type Synchronization Type = Asynchronous Bulk Transfer Type wMaxPacketSize: 0x00C4 = 1 transactions per microframe, 0xC4 max bytes bInterval: 0x04 ===>Descriptor Hex Dump<=== bLength: 0x08 bDescriptorType: 0x25 08 25 01 00 00 00 00 00