[gentoo-user] ALC892 on new motherboard: no sound and no error

Hi,

On my new motherboard there is a on-board audio
chip: Realtek ALC892

After a lot of searching and configuring it seems
to work according to the log - but according to
my ears it does not: There is no sound.

Setup: Motherboard is a MSI Tomahawk Max and
an Nvidia RTX 2060 SUPER (it has a HDMI audio device).

Dmegs says:
[    8.609718] snd_hda_codec_realtek hdaudioC1D0: autoconfig for ALC892: line_outs=4 (0x14/0x15/0x16/0x17/0x0) type:line
[    8.609719] snd_hda_codec_realtek hdaudioC1D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    8.609720] snd_hda_codec_realtek hdaudioC1D0:    hp_outs=1 (0x1b/0x0/0x0/0x0/0x0)
[    8.609720] snd_hda_codec_realtek hdaudioC1D0:    mono: mono_out=0x0
[    8.609721] snd_hda_codec_realtek hdaudioC1D0:    inputs:
[    8.609721] snd_hda_codec_realtek hdaudioC1D0:      Front Mic=0x19
[    8.609722] snd_hda_codec_realtek hdaudioC1D0:      Rear Mic=0x18
[    8.609722] snd_hda_codec_realtek hdaudioC1D0:      Line=0x1a
[    8.623096] input: HD-Audio Generic Front Mic as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input7
[    8.623247] input: HD-Audio Generic Rear Mic as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input8
[    8.623411] input: HD-Audio Generic Line as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input9
[    8.623513] input: HD-Audio Generic Line Out Front as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input10
[    8.623587] input: HD-Audio Generic Line Out Surround as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input11
[    8.623676] input: HD-Audio Generic Line Out CLFE as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input12
[    8.623778] input: HD-Audio Generic Line Out Side as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input13
[    8.623885] input: HD-Audio Generic Front Headphone as /devices/pci0000:00/0000:00:08.1/0000:28:00.4/sound/card1/input14
[    8.702599] snd_hda_codec_generic hdaudioC0D0: ignore pin 0x6, too many assigned pins
[    8.706597] snd_hda_codec_generic hdaudioC0D0: ignore pin 0x7, too many assigned pins
[    8.706599] snd_hda_codec_generic hdaudioC0D0: autoconfig for Generic: line_outs=0 (0x0/0x0/0x0/0x0/0x0) type:line
[    8.706599] snd_hda_codec_generic hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    8.706600] snd_hda_codec_generic hdaudioC0D0:    hp_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    8.706601] snd_hda_codec_generic hdaudioC0D0:    mono: mono_out=0x0
[    8.706601] snd_hda_codec_generic hdaudioC0D0:    dig-out=0x4/0x5
[    8.706602] snd_hda_codec_generic hdaudioC0D0:    inputs:
[    8.722291] usbcore: registered new interface driver cdc_ether
[    8.754670] input: HDA NVidia HDMI as /devices/pci0000:00/0000:00:03.1/0000:26:00.1/sound/card0/input15
[    8.754697] input: HDA NVidia HDMI as /devices/pci0000:00/0000:00:03.1/0000:26:00.1/sound/card0/input16

According to that, soundcard 1 is what I want.
I am using simple stereo speakers, which are connected to the rear I/O
shield of my motherboard, which in turn has direct contact to the
motherboard, so no possible faulty cables are involved. The speakers
are ok since touching the contacts gives a buzzing 100Hz hum.

aplay -L gives:
surround21
    2.1 Surround output to Front and Subwoofer speakers
surround40
    4.0 Surround output to Front and Rear speakers
surround41
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50
    5.0 Surround output to Front, Center and Rear speakers
surround51
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
null
    Discard all samples (playback) or generate zero samples (capture)
samplerate
    Rate Converter Plugin Using Samplerate Library
speexrate
    Rate Converter Plugin Using Speex Resampler
jack
    JACK Audio Connection Kit
oss
    Open Sound System
speex
    Plugin using Speex DSP (resample, agc, denoise, echo, dereverb)
upmix
    Plugin for channel upmix (4,6,8)
vdownmix
    Plugin for channel downmix (stereo) with a simple spacialization
hdmi:CARD=NVidia,DEV=0
    HDA NVidia, Generic Digital
    HDMI Audio Output
usbstream:CARD=NVidia
    HDA NVidia
    USB Stream Output
default:CARD=Generic
    HD-Audio Generic, ALC892 Analog
    Default Audio Device
sysdefault:CARD=Generic
    HD-Audio Generic, ALC892 Analog
    Default Audio Device
front:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    Front speakers
surround21:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Generic,DEV=0
    HD-Audio Generic, ALC892 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
usbstream:CARD=Generic
    HD-Audio Generic
    USB Stream Output

It looks like the default sound card is sound card 1 indeed, which is
the ALC892

But aplay -i gives:
ALSA lib /var/tmp/portage/media-libs/alsa-lib-1.2.2/work/alsa-lib-1.2.2/src/pcm/pcm_dmix.c:1089:(snd_pcm_dmix_open) unable to open slave
aplay: main:830: audio open error: No such file or directory
[1]    18362 exit 1     aplay -i

When trying to play an audio file with mpv gives a similiar error like
that one aplay reports.

Alsamixer has no problems: It let my choose between the two sound
cards and when choosing sound card 1 (ALC892) I can manipulate
the volumes of the different channels.
No channel is muted.
All channels have a reasonable volume setting.

Where is this [CENSORDED] error/bug, which prevents audible sound
output?

Thanks for any helpful advice in advance!

Cheers!
Meino