Hi @ssmith_c , Thank very much for getting back on this question. How custom is your custom device? My custom device is an AOSP (Android) based device which supports UAC2 drivers. I am using the standard UAC2 drivers officially shipped with Android. Does it work on other platforms? My primary objective was to get the device working with macOS. In Linux enviroment the detection of 12 channels was working fine. Does your device reserve enough isochronous bandwidth for 12 channels of 48kHz, 16 bit per sample audio? Data rate for 12 channels 16bit PCM @ 48kHz is ˜9.2 Mbps. The USB 2.0 which I tested have a bandwidth of 480 Mbps. My primary question is, what are the limitation of the UAC2 driver support in latest macOS devices and where can I get for infomation about it? Specially what is the minimum buffer size that apple devices support with UAC2 drivers.

Thank you very much for the inputs. I didn't know that there is a bandwidth limitation on different interfaces when there are multiple USB interfaces are sharing the same USB device. Anyways the firmware in the custom device is not written by me. I only do USB gadget configuration changes to change the bit depth and channel count. The firmware is the standard Linux firmware that shipped with Android OSP. By the way, I checked the usbdiagnose output for 8bit (working condition) and 16bit configs. The only noticeable difference is the Max Packet Size which is 558 (8bit case) and 1024 and 1023 (16bit case). I am not sure why it shows two values in two different places. I have attached the output as files for your reference. 12 channel 8bit 12 channel 16bit On the log collect --last 1m the only meaning full error was from coreaudiod HALS_PlugIn.cpp:834 HALS_PlugIn::HostInterface_PropertiesChanged: the object is not valid Are there any other places which I can check to identify the issue real?

Thank you very much for the clarification. I was able to get a quick fix by reducing the sample rate to 32Khz which is sufficient for now. Thanks a lot for finding the real root cause of my issue. On the points of "works on Linux" the 12 channel is getting detected in Linux but playback was not working fine. I think I forgot to mention that point clearly before.