Very bad audio output for headset on Samsung Galaxy Book5 360 (ALC256)

[MarkusKramer]

Headphone audio output with the 3.5 mm jack has severe distortions - pretty much unusable.

• Distortions occur with multiple headphones (all verified working fine on other devices).
• Volume below ~70% is clean, but audio is then too quiet.
• Internal speakers work fine.
• Did work fine on Windows.

System Information

• Samsung Galaxy Book 5

• NixOS 25.11
• Kernel 6.18.5
• PipeWire 1.4.9
• sof-firmware-2025.05.1-zstd, ADSPFW version: 2.13.0.1
• Realtek ALC256

Debug infos

cat /proc/asound/cards

 0 [sofhdadsp      ]: sof-hda-dsp - sof-hda-dsp
                      SAMSUNGELECTRONICSCO.LTD.-750QHA-P04RHG-NP750QHA_KA4DE

/proc/asound/card0/codec#0
see sound-card0-codec.txt

journalctl -b | grep -i audio

Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Digital mics found on Skylake+ platform, using SOF driver
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: enabling device (0000 -> 0002)
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: DSP detected with PCI class/subclass/prog-if 0x040100
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: bound 0000:00:02.0 (ops intel_audio_component_bind_ops [xe])
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: use msi interrupt mode
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: hda codecs found, mask 5
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: using HDA machine driver skl_hda_dsp_generic now
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: NHLT device BT(0) detected, ssp_mask 0x4
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: BT link detected in NHLT tables: 0x4
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: DMICs detected in NHLT tables: 2
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Firmware paths/files for ipc type 1:
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3:  Firmware file:     intel/sof-ipc4/lnl/sof-lnl.ri
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3:  Firmware lib path: intel/sof-ipc4-lib/lnl
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3:  Topology file:     intel/sof-ipc4-tplg/sof-hda-generic-2ch.tplg
Jan 14 16:28:09 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Loaded firmware library: ADSPFW, version: 2.13.0.1
Jan 14 16:28:10 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Booted firmware version: 2.13.0.1
Jan 14 16:28:10 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Topology: ABI 3:29:1 Kernel ABI 3:23:1
Jan 14 16:28:10 kirk kernel: sof-audio-pci-intel-lnl 0000:00:1f.3: Loaded firmware library: ADSPFW, version: 2.13.0.1
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0: autoconfig for ALC256: line_outs=1 (0x14/0x0/0x0/0x0/0x0) type:speaker
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0:    hp_outs=1 (0x21/0x0/0x0/0x0/0x0)
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0:    mono: mono_out=0x0
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0:    inputs:
Jan 14 16:28:10 kirk kernel: snd_hda_codec_alc269 ehdaudio0D0:      Mic=0x19
Jan 14 16:28:11 kirk systemd[1]: Starting PipeWire PulseAudio System Socket...
Jan 14 16:28:11 kirk systemd[1]: Listening on PipeWire PulseAudio System Socket.
Jan 14 16:28:55 kirk systemd[1]: Started PipeWire PulseAudio Service.
Jan 14 16:34:43 kirk systemd[1]: Stopping PipeWire PulseAudio Service...
Jan 14 16:34:43 kirk systemd[1]: Stopped PipeWire PulseAudio Service.
Jan 14 16:34:44 kirk systemd[1]: Closed PipeWire PulseAudio System Socket.

Any advice would be appreciated. I'm happy to provide more details.