[USB-Audio - Xonar SoundCard, playback] Playback problem

[Roman]

PulseAudion issue for Xonar SE. S/PDIF output is not used when output is configured to Digital Output SPDIF (IEC958). I assume it's incorrectly confused with analog audio output.
Alsa digital output via TOSlink is ok, namely plughw:CARD=SoundCard,DEV=2 - works ok (audcious used to play it)

using
> aplay -D plughw:1,2 Cymbal.wav
is also OK

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 4.15.0-76.86-generic 4.15.18
Uname: Linux 4.15.0-76-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: rrrr 1661 F.... pulseaudio
 /dev/snd/pcmC1D2p: rrrr 9879 F...m audacious
 /dev/snd/controlC1: rrrr 1661 F.... pulseaudio
                      rrrr 9879 F.... audacious
CurrentDesktop: XFCE
Date: Tue Feb 4 20:27:05 2020
InstallationDate: Installed on 2016-05-18 (1357 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:SoundCard failed
Symptom_Card: Xonar SoundCard - Xonar SoundCard
Symptom_Type: Only some of outputs are working
Title: [USB-Audio - Xonar SoundCard, playback] Playback problem
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/04/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F2
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: N3150ND2H
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: To be filled by O.E.M.
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 1
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF2:bd12/04/2015:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnN3150ND2H:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct1:cvrToBeFilledByO.E.M.:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: To be filled by O.E.M.
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Gigabyte Technology Co., Ltd.