Some speakers turn themselves off automatically when they don't detect any sound on the line for a certain amount of time.
So when you want to have your monitoring application ring the alarm on the speaker, you need to be aware of it so you don't miss it.
Depending on the speaker you may need to be continuously playing some very low volume audio to prevent them from auto-turning off.
Standard is very high frequency -- outside of audible range. It's a good hack. Especially helpful for disabling automatic gain control.
It takes most digital decoders a little while to start streaming again when a new digital signal comes in. I’ve noticed it in every setup using digital audio output from a PC I’ve ever used.
To fix it I believe it’s possible to send encoded complete silence, and that still works to stop the decoder from stopping.
I don’t know why there would be a delay, but my guess is that it’s something like waiting for the next “block” of audio to start to start.
I’ve noticed when bitstreaming compressed audio formats that the delay is longer, but also a bit arbitrary which I suspect is because the next block start position depends on where exactly you paused the video.