I think that maybe what is happening is that you are trying to bitstream via SPDIF, but because it is the only audio endpoint available in the system all system sounds (and MP GUI sounds when press buttons etc) are also trying to be sent via SPDIF. If the playback audio is not PCM (e.g. AC3) then Windows can't mix other audio with it, so maybe it just switches the streams (and effectively removes/blocks the 'bitstream' audio when it's playing the other sounds). This then breaks the playback....
So probably you need to make sure that there is always a non-SPDIF 'default' audio endpoint (playback device) available - plugging an empty jack plug or extension lead into the headphone or line output socket may be enough to convince the IDT drivers that something is connected.
So probably you need to make sure that there is always a non-SPDIF 'default' audio endpoint (playback device) available - plugging an empty jack plug or extension lead into the headphone or line output socket may be enough to convince the IDT drivers that something is connected.
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