S/PDIF and switching from PCM to compressed 5.1 on ASUS XONAR SE

Hello, I wish to switch my sound card (ASUS XONAR SE) from 2 channel (PCM) to 5.1. I have the XONAR connected to my receiver via a TOSLINK cable. The XONAR uses a cmedia 6620A audio processor, and Realtek ALC 1220X codec.

When I check Setup > Sound and select S/PDIF output I do not have any options for surround sound settings.


I haven’t tried it, but a little googling seems to indicated that you need to “Encode PCM 5.1 24-bit audio into a A/52 16-bit audio stream”.


I read that most S/PDIF connections only have enough bandwidth for 2 uncompressed (PCM) channels. So you will have to send a compressed (DTS) signal through the line to transmit 5.1 channels over a S/PDIF TOSLINK.

Hello Gregory, I think you are correct regarding S/PDIF and 2 channel PCM or compressed 5.1.

I think I could use the ASUS XONAR SE Windows 10 drivers to select compressed 5.1 as the output from the S/PDIF if I was using Windows 10. It seems to me that the ability to configure the audio processor or Realtek codec for S/PDIF output as compressed 5.1 is not in Fedora 34.

I think that in Settings > Sound I should be able to select XONAR SE (S/PDIF) and 5.1 and then test the 5 speakers and subwoofer. I can select XONAR SE (S/PDIF) and then test a two speaker configuration not the 5.1 configuration.

Something to consider with audio on 34:
Fedora 34 uses pipewire by default while 33 and earlier used pulseaudio. It may be that one of the still missing parts of pipewire is related to your problem, and contacting the developers directly or filing a bug report may get a quick fix. It also is possible to revert to pulseaudio and that could be an easy test of where the problem lies. A quick google search for “switching from pipewire to pulseaudio on fedora 34” gives a lot of results.

FYI. It looks like there is an open issue about adding “Proper support for multi-channel audio interfaces” to pipewire.

Until that issue is closed, you’re only option is probably to switch to one of the other sound systems that might do what you want – pulseaudio, jack, or alsa.