When I play music I send it to an AV amp using a digital out. I have an HDMI connection that has to go through the TV to the amp, and a optical on the motherboard that goes direct to the amp. The optical out is the better choice for music.

The problem I have is that after a random amount of time (usually at least once every 5 - 10 mins) the output device in the PulseAudio volume control changes from HD-Audio Generic Digital Stereo (IEC958) to Unknown output and the sound drops briefly.

It doesn't do this went the output is set to HDMI.

How can I trouble shoot this issue? I'm not sure if it's an Elementary problem, PulseAudio problem, or a hardware fault. Hopefully once I know the problem I can investigate a solution.


1 Answer 1


i disagree optical is better for music unless your receiver is a pair of empty food cans. digital is digital. if you spdif you are trying to avoid processing on the reciever? i dont see benefit. digital is digital and conversion aside the connection over spdif or hdmi is lossless. but whatever.

your optical cable is probably junk (stepped on, dirty, etc) and dropping the digital connection due to a signal quality issue. try with new cable. i can't test because i dont use optical out anymore. this doesn't sound like a software issue since audio in linux usually 'just works'.

  • I think maybe the TV does some processing before it sends it back out. There is a difference in the sound across the two option.I don't think it's the cable's fault. There's no feedback coming back from an optical cable is there? If I unplug the optical from the back of the amp then the PC doesn't know. By hardware fault I mean the motherboard.
    – Michael wx
    Sep 2, 2019 at 9:04
  • And having had high end sound equipment for over 20 years I can assure you my optical cable is not junk, nor has it been stepped on, nor have I got it dirty. The receiver is not a pair of tin cans, it's a very nice Denon amp with a couple of thousand quid of speakers. What sounds better through what will be totally subjective, and to my ear in my set up the the optical (maybe just because it's direct to the amp) sounds that tiny bit better. But thank you for taking time to answer.
    – Michael wx
    Sep 5, 2019 at 18:11

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