...about event mode, wasapi
This is indicated by the driver, from an API call. It has nothing to do with the endpoint (so Speaker, SPDIF, maxnix). It's the Asus driver. The picture shows a typical result (typical if such a thing is reported; it's the only one I know of that does this). The API is (my call to it)
hr = IpropertyStorePtr->GetValue(myPKEY_AudioEndpoint_Supports_EventDriven_Mode, &isEventOkayVar);
where myPKEY_AudioEndpoint_Supports_EventDriven_Mode is
DEFINE_GUID(myGUID_AudioEndpoint_Supports_EventDriven_Mode, 0x1da5d803, 0xd492, 0x4edd, 0x8c, 0x23, 0xe0, 0xc0, 0xff, 0xee, 0x7f, 0x0e);
Means nothing to most, but in case you wanted to know why this is, or could use it yourself. It's pretty much a given anyone doing waspi will already know this call.