Hello Matthew, > I believe the intent of this audio subsystem check is to ensure > it's not stepping on any DirectKS clients' toes. What undesired could happen in such case? If a driver exposes a pin supporting a single instance only, there is no problem. If a pin exposed allows multiple instances, a driver knows how to handle them correctly. > Can you help me understand the scenario that requires simultaneous > DirectKS and audio subsystem clients for a given pin? A simplest example is an ASIO application working with a plain WDM/KS device without its proprietary ASIO driver. In such case, ASIO4ALL proxy is used, becoming a KS client. Since ASIO4ALL allocates the first pin instance, no MME, DirectSound or WASAPI clients can access the pin. The only workaround is to start MME/DirectSound/WASAPI client first and then start ASIO client. Some applications offer their own KS interfaces for recording to ensure reliability (WASAPI exclusive mode implementation has at least one known bug in Win7 that had been fixed in Win8). Regards, Eugene ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/