docs: catalogue Linux audio input and output failure modes

This catalogues real, user-reported ways the microphone and speakers fail on Linux, to feed the audio doctor's triage. It holds 58 input and 59 output distinct root causes, across eight layers each: kernel/driver/firmware, ALSA, PipeWire, Bluetooth, HDMI, USB, app/portal, hardware. Every entry carries its symptom, cause, concrete fix, a sudo/reboot tag, and a source.

The sudo/reboot tag is the triage lever. A no-sudo, no-reboot fix is a candidate for a doctor remedy. A firmware, BIOS, or physical fix can only ever be a printed instruction. Triage into build, guide, or out is the next pass.

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+#+TITLE: Linux Audio Failure Taxonomy — for the audio doctor
+#+AUTHOR: Craig Jennings
+#+DATE: 2026-07-10
+
+* Purpose
+
+A catalogue of real, user-reported ways Linux audio input (microphone) and output (speakers/headphones) fail, grounded in forum and issue-tracker reports. Built to feed the audio doctor: each entry will later be triaged into build (an auto/confirm remedy the doctor applies), guide (a diagnosis plus the exact fix the user runs), or out (beyond the doctor's reach). Triage is a later pass — for now the goal is breadth.
+
+Target: 50 input failure modes and 50 output failure modes, or exhaustion. Each entry names the layer, the symptom as a user reports it, the root cause, the known resolution, and a source.
+
+* Input (microphone) failure modes
+
+Built 2026-07-10 from a parallel research sweep across eight layers (kernel/driver/firmware, ALSA, PipeWire/WirePlumber, Bluetooth, USB, app/portal, hardware, config/misc). 64 raw entries deduped to 58 distinct root causes. Each names the layer, the user-reported symptom, the cause, the known fix (with the concrete command where one exists), whether the fix needs root or a reboot, and a source. The =sudo/reboot= field is the first triage signal: a no-sudo, no-reboot fix is a candidate for an auto or guide remedy; a both/physical fix can only ever be a guide.
+
+** Kernel / driver / firmware
+
+- Missing SOF firmware for a DSP-attached mic (both). Internal mic not recognised on a modern Intel laptop; speakers fine. Digital mic hangs off the Intel DSP and needs Sound Open Firmware. Fix: =pacman -S sof-firmware alsa-ucm-conf=, reboot. [[https://bbs.archlinux.org/viewtopic.php?id=287361][arch 287361]]
+- Stale =dmic_detect=0= / =dsp_driver=1= modprobe override (both). Mic dead after an old "fix"; no DMIC input. A leftover =/etc/modprobe.d= option forces the legacy HDA path and bypasses the SOF driver that owns the digital mic. Fix: delete the override, install sof-firmware, rebuild initramfs, reboot. [[https://bbs.archlinux.org/viewtopic.php?id=260827][arch 260827]]
+- Missing codec model / ADC quirk, ALC236/ALC256 (both). Capture controls visible and unmuted, but =arecord= records silence. =snd_hda_intel= lacks the board-specific pin/ADC-gain quirk, so the ADC is never routed. Fix: =options snd-hda-intel model=...= workaround; real fix is a kernel patch_realtek entry. [[https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/2142994][launchpad 2142994]]
+- Kernel-version regression broke a working mic (both). Internal mic recorded fine until a kernel update, then stopped. A regression between builds broke ALC256 capture routing. Fix: boot the last-good kernel or install linux-lts until a fixed build lands. [[https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2117316][launchpad 2117316]]
+- AMD ACP6x DMIC needs a DMI quirk, not firmware (both). Ryzen laptop internal array mic absent or silent; sof-firmware changes nothing. The acp6x mic array needs the laptop's DMI entry in the =SND_SOC_AMD_YC_MACH= quirk table. Fix: newer kernel with the board's DMI quirk, or add the entry and rebuild. [[https://bbs.archlinux.org/viewtopic.php?id=311093][arch 311093]]
+- Missing NHLT ACPI table in firmware (both). No DMIC; dmesg shows "NHLT table not found". The platform firmware omits the NHLT table, so SOF can't discover the digital-mic count. Fix: flash firmware that supplies NHLT, or override the dmic count via SOF modprobe params. [[https://github.com/MrChromebox/firmware/issues/920][mrchromebox 920]]
+- Brand-new AMD ACP7.0 (Strix Halo) has no mic driver/UCM yet (both). Internal DMIC non-functional on very recent AMD hardware. The kernel ACP7.0 SOF driver and UCM profile weren't upstreamed yet. Fix: wait for the kernel + alsa-ucm-conf that add ACP7.0 support. [[https://github.com/alsa-project/alsa-ucm-conf/issues/745][ucm-conf 745]]
+
+** ALSA (profiles, UCM, mixer, pins, state)
+
+- Wrong card profile, no input route (no). Speakers work, no capture device appears, only a ".monitor". The card sits on an output-only profile so ALSA never exposes the capture PCM. Fix: =pactl set-card-profile <card> output:analog-stereo+input:analog-stereo=. [[https://bbs.archlinux.org/viewtopic.php?id=269173][arch 269173]]
+- ACP vs UCM detection mismatch (no). alsa-card-profiles fixes the mic but PipeWire breaks it again. WirePlumber's ACP probing (or an auto-selected UCM) mis-detects the capture ports. Fix: set =api.alsa.use-acp = false= (or =use-ucm = true=) in WirePlumber, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=291807][arch 291807]]
+- Capture / Internal Mic switch muted in mixer (no). Mic recognized but records silence. The "Capture" or "Internal Mic" mixer switch is toggled off in ALSA state. Fix: =amixer set Capture cap= (or Space on the item in alsamixer). [[https://wiki.archlinux.org/title/Advanced_Linux_Sound_Architecture/Troubleshooting][archwiki alsa]]
+- Input Source enum on the wrong pin (no). Plugged-in mic silent; the wrong jack is live. The "Input Source" control selects a different pin (Rear vs Front Mic). Fix: =amixer set 'Input Source' 'Front Mic'=. [[https://bbs.archlinux.org/viewtopic.php?id=145531][arch 145531]]
+- alsactl restores a muted capture at boot (yes). Mic works after manual unmute, muted again every reboot. alsa-restore replays a saved state with capture muted. Fix: unmute, then =sudo alsactl store=. [[https://bbs.archlinux.org/viewtopic.php?id=183211][arch 183211]]
+- Internal Mic Boost at zero (no). Mic works but far too quiet to use. The "Mic Boost" gain sits at 0. Fix: =amixer set 'Internal Mic Boost' 100%=. [[https://forum.manjaro.org/t/microphone-array-input-too-quiet-alsamixer-mic-boost-not-changing-anything/90904][manjaro 90904]]
+- Auto-Mute Mode disabling capture (no). Internal mic cuts out, often tied to headphone-jack state. The codec's "Auto-Mute Mode" mutes internal capture when a jack is sensed. Fix: =amixer set 'Auto-Mute Mode' Disabled=. [[https://wiki.archlinux.org/title/Advanced_Linux_Sound_Architecture/Troubleshooting][archwiki alsa]]
+- Wrong default capture in .asoundrc (no). Apps with no picker record from the wrong card. =pcm.!default= points at the wrong capture card. Fix: set =pcm.!default= to the right =plughw= in =~/.asoundrc=; find it with =arecord -l=. [[https://bbs.archlinux.org/viewtopic.php?id=274238][arch 274238]]
+- Missing UCM capture profile for the codec (no). No input profile offered at all for the built-in mic. alsa-ucm-conf lacks a UCM definition for the card. Fix: fall back to ACP (=use-ucm = false=) or install/patch the card's UCM config. [[https://github.com/alsa-project/alsa-ucm-conf/issues/594][ucm-conf 594]]
+
+** PipeWire / WirePlumber
+
+- WirePlumber fails to start on old/empty config (no; sudo only if under /etc). No audio devices at all after an update; wpctl lists nothing. WirePlumber won't parse a leftover 0.4-era config or empty drop-in and dies. Fix: remove the offending config, =systemctl --user restart wireplumber=. [[https://bbs.archlinux.org/viewtopic.php?id=294649][arch 294649]]
+- Capture source muted on startup, stale WP state (no). Mic dead every boot until you mute then unmute it. Stale state in =~/.local/state/wireplumber= restores the source muted. Fix: stop wireplumber, =rm -r ~/.local/state/wireplumber=, start; or =wpctl set-mute <id> 0=. [[https://bbs.archlinux.org/viewtopic.php?id=297727][arch 297727]]
+- Default source is a monitor / wrong device, and not persisted (no). Apps pick up silence or loopback; the "mic" is a sink Monitor, or the default resets to the wrong card each reboot. WirePlumber's auto-selection picks the wrong node and doesn't persist a manual default. Fix: =wpctl set-default <mic-id>=, and pin it with a node.name rule to survive reboot. [[https://bbs.archlinux.org/viewtopic.php?id=285076][arch 285076]]
+- pipewire-pulse dead or wrong socket (no). pactl apps report "connection refused"; pw-cat may still work. pipewire-pulse isn't running, or XDG_RUNTIME_DIR is wrong so =/run/user/1000/pulse/native= is missing. Fix: correct XDG_RUNTIME_DIR, =systemctl --user restart pipewire pipewire-pulse wireplumber=. [[https://bbs.archlinux.org/viewtopic.php?id=281062][arch 281062]]
+- Node suspended, never resumes (no). Mic works once, then silent when idle; drop when an app reopens it. =session.suspend-timeout-seconds= parks the source and it fails to wake on some 0.5.x builds. Fix: drop-in setting =session.suspend-timeout-seconds = 0=, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=309630][arch 309630]]
+- A filter/virtual source shadows the real mic (no). Only a virtual "echo-cancel" or EasyEffects source shows; apps capture nothing, or apps get the raw unfiltered mic instead of the processed one. module-echo-cancel / filter-chain / EasyEffects creates a virtual source with the wrong node.target or default. Fix: fix node.target, or =wpctl set-default <right-id>=. [[https://docs.pipewire.org/page_module_echo_cancel.html][pw echo-cancel]]
+- Broken ~/.config/wireplumber override disables the node (no). Internal mic stops defaulting after a config edit; system configs seem ignored. A malformed or disabling user drop-in shadows the system defaults. Fix: remove/repair the drop-in, restart wireplumber. [[https://discussion.fedoraproject.org/t/wireplumber-not-connecting-microphone/63354][fedora 63354]]
+- Forced or mismatched sample rate locks the source (no). Mic stuck at 48 kHz, or silent, or apps fail to open it; also seen on USB interfaces that only do 48k. A global =default.clock.rate= / =node.force-rate= pins the graph to a rate the device or app can't negotiate, with no allowed-rates fallback. Fix: set =default.clock.allowed-rates= to a list rather than forcing one, restart pipewire; runtime =pw-metadata -n settings 0 clock.force-rate 0=. [[https://bbs.archlinux.org/viewtopic.php?id=288932][arch 288932]]
+
+** Bluetooth
+
+- Headset stuck in A2DP, no mic input (no). Headphones play great but the mic never appears. A2DP is sink-only, no microphone source. Fix: =pactl set-card-profile <bt-card> headset-head-unit=. [[https://bbs.archlinux.org/viewtopic.php?id=280718][arch 280718]]
+- oFono installed but unconfigured, HFP profile absent (yes, to remove pkg). No HFP/HSP profile listed after moving to PipeWire. oFono grabs the HFP backend but is never configured. Fix: remove oFono (=pacman -R ofono=) or set =bluez5.hfphsp-backend = "native"=, restart pipewire. [[https://bbs.archlinux.org/viewtopic.php?id=269195][arch 269195]]
+- mSBC codec not enabled / unavailable (no). Headset won't offer mSBC; mic is muffled CVSD or missing. mSBC role/codec not enabled in WirePlumber. Fix: set =bluez5.codecs = [ sbc sbc_xq msbc ]= and enable =hfp_hf=, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=266252][arch 266252]]
+- Auto-switch to headset profile never triggers (no). Open a call app and the mic stays dead; nothing flips to HFP. WirePlumber's autoswitch isn't firing. Fix: confirm autoswitch is on, or switch manually with set-card-profile. [[https://forum.endeavouros.com/t/my-bluetooth-headphone-mic-not-reconisied-after-switching-to-pipewire/17586][endeavour 17586]]
+- Codec negotiation silently drops to baseline (no). Mic works but quality is terrible; preferred codec never applies. Negotiation fails and PipeWire quietly falls back. Fix: pin codec order in a WirePlumber =bluez5.codecs= rule, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=300230][arch 300230]]
+- Adapter/headset rejects hsp_ag and hfp_ag together (no). Enabling both roles breaks the profile on some headsets (Sony WH-1000XM3). Fix: restrict roles to =hfp_hf=/=hfp_ag= (drop =hsp_ag=), restart wireplumber. [[https://pipewire.pages.freedesktop.org/wireplumber/daemon/configuration/bluetooth.html][wp bluetooth]]
+- BT mic invisible to arecord / /proc/asound (no). ALSA tools show no Bluetooth mic, so the user thinks it's undetected. The bluez5 mic is a PipeWire node, not an ALSA card, by design. Fix: list it with =wpctl status=, record with =pw-record=. [[https://wiki.archlinux.org/title/PipeWire][archwiki pipewire]]
+- Switching to the mic profile tanks playback quality (no; expected). Music turns to tinny phone-call audio the moment the mic works. HFP shares narrow bandwidth for duplex. Fix: expected tradeoff; switch back to A2DP off-call, or enable mSBC to soften it. [[https://webcodr.io/2024/10/fixing-no-a2dp-with-bluetooth-headsets-on-linux/][webcodr]]
+
+** USB microphones
+
+- USB autosuspend powers the mic down while idle (both). Mic works at first, then silent or vanishes after sitting unused. Kernel autosuspend puts the idle device to sleep and it never wakes cleanly. Fix: a udev rule pinning =power/control=on= for the device, or =usbcore.autosuspend=-1=. [[https://bbs.archlinux.org/viewtopic.php?id=199504][arch 199504]]
+- Focusrite Scarlett needs a quirk / device_setup (both). XLR interface enumerates but capture is broken or wrong-channel. The device mis-reports config; snd-usb-audio needs a quirk (or the scarlett2 driver, built-in from 6.7). Fix: =options snd_usb_audio ... device_setup=1= on older kernels, or run kernel >= 6.7. [[https://blog.rtrace.io/posts/fedora-support-focusrite-scarlett/][rtrace scarlett]]
+- Intermittent disconnect with URB resets (no). Mic drops mid-use; dmesg shows disconnect and "cannot submit urb". A flaky bus/hub/cable link causing URB failures. Fix: use a direct motherboard port or powered hub, swap the cable. [[https://linux-usb.vger.kernel.narkive.com/MdlWpDZG/cannot-submit-urb-0-error-22-internal-error-followed-by-usb-hung-tasks][linux-usb list]]
+- Bus/hub can't supply enough power (no). Interface fails to power up or drops out, often through an unpowered hub. A bus-powered interface exceeds what a USB2 port or passive hub delivers. Fix: powered hub or the interface's PSU; a direct rear port. [[https://bbs.archlinux.org/viewtopic.php?id=267926][arch 267926]]
+- Mic dead after boot until physically replugged (both). USB mic gives no input after cold boot; replug fixes it every time. Ports stay powered through shutdown, so the device never power-cycles to enumerate at boot. Fix: enable ErP / "power off USB on shutdown" in BIOS. [[https://bbs.archlinux.org/viewtopic.php?id=280206][arch 280206]]
+- WirePlumber cached a no-input card profile for the USB device (no). Card present but no capture source appears. WirePlumber remembers a profile with input off, or a corrupt state cache. Fix: =pactl set-card-profile <card> input:...=; if it won't stick, clear =~/.local/state/wireplumber=. [[https://bbs.archlinux.org/viewtopic.php?id=294444][arch 294444]]
+
+** Application / browser / portal / sandbox
+
+- Wayland browser returns an empty mic list to WebRTC (no). Google Meet shows no microphone, no permission prompt (Firefox/Chrome/Zen on Wayland). The WebRTC PipeWire capturer isn't active so enumerateDevices() yields nothing. Fix: launch with =--enable-features=WebRTCPipeWireCapturer --ozone-platform=wayland= (Chromium) or the portal prefs (Firefox). [[https://github.com/zen-browser/desktop/issues/9745][zen 9745]]
+- Flatpak app lacks device / pulse permission (no). Discord (Flatpak) can't hear the mic. The sandbox withholds the mic; no =--device= or pulse access. Fix: =flatpak override --user --device=all <app>= (or Flatseal). [[https://lionir.ca/flathub-discord-permissions-explained/][flathub discord]]
+- Flatpak app has no audio socket exposed (no). Zoom/Viber Flatpak sees no mic at all. The sandbox lacks the audio socket (=--socket=pulseaudio= / =xdg-run/pipewire-0=). Fix: =flatpak override --user --socket=pulseaudio <app>=. [[https://forums.linuxmint.com/viewtopic.php?t=456895][mint 456895]]
+- Snap audio-record interface not connected, or AppArmor mediation (yes). Mumble/OBS snap gets no mic; or pipewire-pulse breaks on a confined client's connect. The =audio-record= interface is off by default and doesn't auto-connect; the AppArmor/LSM path can block or crash. Fix: =sudo snap connect <snap>:audio-record=, or the pipewire-pulse SystemCallFilter drop-in. [[https://forum.snapcraft.io/t/i-am-unable-to-record-audio-from-several-snaps/18703][snapcraft 18703]]
+- xdg-desktop-portal not started under Hyprland (no; relogin). Screen/mic capture silently fails, no portal prompt on Hyprland. The portal needs =graphical-session.target=, which a bare Hyprland exec never raises. Fix: import the environment and raise the session target in the Hyprland startup. [[https://github.com/hyprwm/Hyprland/discussions/10841][hyprland 10841]]
+- Permission-store caches a stale "deny" (no). An app was denied once and never re-prompts. The portal permission store persists the earlier "no". Fix: =flatpak permission-reset <app-id>= (or =permission-remove devices microphone=). [[https://man.archlinux.org/man/flatpak-permission-reset.1.en][flatpak permission-reset]]
+- Browser per-site mic permission set to Block (no). A site says mic blocked though the OS mic works. Chrome stores a per-origin "Not allowed" rule. Fix: Site settings, reset Microphone to Ask/Allow. [[https://support.google.com/chrome/answer/2693767][chrome mic]]
+- An app grabs the mic exclusively, starving others (no). While OBS/Discord runs, other apps get no mic; or arecord reports the device busy. The app opens the node (or raw ALSA hw) in exclusive mode. Fix: point the app at shared pipewire capture instead of the raw device source. [[https://obsproject.com/forum/threads/mic-echos-into-all-outputs-arch-pipewire.150207/][obs 150207]]
+
+** Hardware / physical / BIOS
+
+- Hardware mic-mute / privacy kill-switch (physical). All ALSA levels up and unmuted, still no signal. A physical slider or EC-level mute holds capture off below software. Fix: toggle the physical switch; some models need a BIOS re-enable. [[https://bbs.archlinux.org/viewtopic.php?id=182671][arch 182671]]
+- Laptop mic-mute key not honored, e.g. ThinkPad Fn+F4 (no). The LED toggles but the key never mutes/unmutes, and pactl is out of sync. The key maps to F20 and the EC mute isn't wired to the audio stack. Fix: bind keycode 190 (F20) to a pactl source-mute toggle. [[https://bbs.archlinux.org/viewtopic.php?id=268269][arch 268269]]
+- Combo jack keeps the internal mic selected (yes, if model option). Headset plugged in but the internal mic stays active. The shared combo jack doesn't expose "Headset Microphone"; an auto-mute/model quirk. Fix: pick "Headset Microphone" in pavucontrol, or =model=headset-mode= / disable Auto-Mute. [[https://bbs.archlinux.org/viewtopic.php?id=252594][arch 252594]]
+- Jack retasked to the wrong function (both). A mic port never registers a device, or is seen as line-out. A buggy BIOS pin-config assigns the jack the wrong default function. Fix: =hdajackretask=, override the pin to Microphone, install boot override, reboot. [[https://fossies.org/linux/alsa-tools/hdajackretask/README][hdajackretask]]
+- TRRS wiring mismatch, CTIA vs OMTP (physical). Audio plays but the headset mic is dead. The headset is wired to the opposite standard (mic/ground swapped). Fix: an OMTP-to-CTIA adapter, or a USB dongle. [[https://forums.linuxmint.com/viewtopic.php?t=336989][mint 336989]]
+- Broken / loose 3.5mm jack (physical). Mic cuts in/out when the cable is flexed, or nothing detected. Bent contacts or a cracked solder joint. Fix: confirm on another device; use a USB dongle if the jack is dead. [[https://forums.linuxmint.com/viewtopic.php?t=452191][mint 452191]]
+- A webcam's built-in mic is a separate USB device (yes, for udev rule). The system switches to low-quality audio from the webcam the user didn't know had a mic. The webcam enumerates as its own USB Audio Class interface. Fix: select the intended mic as default, or blacklist the webcam's audio interface with a udev rule. [[https://www.mjt.me.uk/posts/blacklisting-certain-microphones-linux/][mjt blacklist]]
+- BIOS/UEFI disables the internal mic or audio controller (both). No capture device present at all in Linux. A firmware setting turns off the mic or the audio controller. Fix: re-enable it in BIOS setup. [[https://www.dell.com/community/en/conversations/inspiron/bios-setting-to-disable-onboard-microphone/7331179][dell inspiron]]
+
+** Config / permissions / misc
+
+- PulseAudio and pipewire-pulse both installed (yes). Mic worked on PulseAudio, took no input after switching; both seem to run. Leftover pulseaudio auto-spawns and grabs the device, fighting pipewire-pulse. Fix: remove pulseaudio, set =autospawn = no=, enable =pipewire-pulse.socket=. [[https://bbs.archlinux.org/viewtopic.php?id=283345][arch 283345]]
+- User lacks realtime privileges / RTKit denied (both). Mic crackles or drops; logs show "could not make thread realtime using RTKit". No polkit session and user not in the realtime group. Fix: =pacman -S realtime-privileges=, add user to =realtime=, re-login. [[https://forum.manjaro.org/t/pulseeffects-cant-get-realtime-priority/42584][manjaro 42584]]
+- XDG_RUNTIME_DIR unset in ssh/cron/non-login session (no). Recording works in the desktop terminal but fails from ssh or cron. Non-login sessions skip pam_systemd, so the socket in =/run/user/<uid>= isn't found. Fix: run as the seat user with =XDG_RUNTIME_DIR= set. [[https://bbs.archlinux.org/viewtopic.php?id=286176][arch 286176]]
+- Auto-gain (AGC) pulling the mic level toward zero (no). The mic gets progressively quieter; something keeps lowering the input volume. An app or WirePlumber is allowed to auto-adjust the source gain and only ratchets down. Fix: a WirePlumber access rule blocking the client from changing gain. [[https://www.lumeh.org/wiki/audio/stop-adjusting-my-microphone/][lumeh]]
+
+* Output (speakers / headphones) failure modes
+
+Built 2026-07-10 from a parallel sweep across eight output-specific layers (kernel/driver/firmware, ALSA mixer/pin, PipeWire routing, Bluetooth, HDMI/DisplayPort, USB DAC + hardware/BIOS, app/browser, and audio quality: crackle/xrun/latency). 64 raw entries deduped to 59 distinct root causes. Same fields and =sudo/reboot= triage signal as the input section.
+
+** Kernel / driver / firmware
+
+- SOF DSP firmware not installed (both). Fresh install shows only "Dummy Output"; nothing in =/proc/asound/cards=; dmesg "failed to load DSP firmware". The Intel DSP needs Sound Open Firmware to boot. Fix: =pacman -S sof-firmware=, reboot. [[https://github.com/basecamp/omarchy/issues/6110][omarchy 6110]]
+- Cirrus CS35L41 smart amp, missing ACPI _DSD (both). Card present, speakers dead on 2023 ASUS/HP; dmesg "ACPI _DSD Properties are missing for HID CSC3551". BIOS omits the props the =cs35l41-hda= driver needs, and the amp firmware is required. Fix: install =firmware-cirrus=, apply the _DSD override, or kernel >= 6.9 / BIOS update. [[https://asus-linux.org/guides/cirrus-amps/][asus-linux cirrus]]
+- TI TAS2781 smart amp, driver/firmware absent (both). Lenovo Legion speakers silent; "Direct firmware load for TIAS2781RCA2.bin failed". The =SND_HDA_SCODEC_TAS2781= driver isn't built and the RCA firmware is undistributable. Fix: kernel with the option enabled + TI firmware in =/lib/firmware=. [[https://bbs.archlinux.org/viewtopic.php?id=289379][arch 289379]]
+- Wrong HDA model autodetection, speaker dead (both). ALSA works but the internal speaker is silent; only headphone/HDMI plays. =snd_hda_intel= picked the wrong codec model so the speaker pin/amp isn't enabled. Fix: =options snd-hda-intel model=<quirk>= in =/etc/modprobe.d/=. [[https://bbs.archlinux.org/viewtopic.php?pid=1109929][arch 1109929]]
+- snd_soc_skl grabs the card, only Dummy Output (both). After a kernel update, sound gone; only "Dummy Output". The SST driver claims the controller and the DMIC probe fails, leaving no playback path. Fix: =options snd-hda-intel dmic_detect=0= + =blacklist snd_soc_skl=. [[https://www.linuxuprising.com/2018/06/fix-no-sound-dummy-output-issue-in.html][linuxuprising]]
+- AMD Ryzen HDA codec probe timeout (both). No internal speakers; =/proc/asound= shows only the HDMI codec. The analog codec probe fails ("no codecs initialized") on Renoir/Cezanne. Fix: newer kernel/firmware; =probe_mask=1= / =dmic_detect=0= workaround. [[https://forums.linuxmint.com/viewtopic.php?t=448906][mint 448906]]
+- Kernel regression killed HDA output (both). Speakers worked, went silent after a kernel bump. An HDA/codec regression in the new kernel. Fix: boot the previous kernel or linux-lts until a fix lands. [[https://bbs.archlinux.org/viewtopic.php?id=278370][arch 278370]]
+
+** ALSA (mixer, pins, jack, state)
+
+- Master / PCM channel muted, MM in alsamixer (no). No sound from any output. The mixer channel is left muted. Fix: =amixer sset Master unmute; amixer sset PCM unmute=. [[https://bbs.archlinux.org/viewtopic.php?id=200955][arch 200955]]
+- Auto-Mute Mode silences speakers (no). Speakers muted when headphones are (un)plugged, or stay muted with nothing plugged. The codec's Auto-Mute ties speaker output to jack-sense. Fix: =amixer sset 'Auto-Mute Mode' Disabled=. [[https://bbs.archlinux.org/viewtopic.php?id=185098][arch 185098]]
+- alsactl restores a muted master at boot (yes). Sound works after manual unmute, muted every reboot. alsa-restore replays a muted state, or runs before the card enumerates. Fix: unmute, =sudo alsactl store=; add a delay to alsa-restore if it races. [[https://bugs.archlinux.org/task/35438][arch bug 35438]]
+- Front/Surround/Center/LFE channel muted (no). Only some speakers play. Per-channel mixer controls muted by default on multi-channel codecs. Fix: =amixer set Surround/Center/LFE 100% unmute=; verify =speaker-test -c 6=. [[https://bbs.archlinux.org/viewtopic.php?id=172793][arch 172793]]
+- Dead headphone pin needs hdajackretask (both). Speakers work, headphone jack silent and undetected. A BIOS pin-config leaves the headphone pin unconnected. Fix: =hdajackretask=, override the pin to Headphone, install boot override, reboot. [[https://bbs.archlinux.org/viewtopic.php?id=229296][arch 229296]]
+- Phantom jack-sense keeps speakers muted (yes). Speakers stay muted because the codec reports headphones plugged when nothing is. A spurious/stuck jack-detect state. Fix: force re-detect via hdajackretask reconfigure, or disable jack-detect for the speaker path. [[https://bbs.archlinux.org/viewtopic.php?id=265363][arch 265363]]
+- Wrong codec model quirk, no headphone or speaker (both). The auto-parser misdetects the board and picks the wrong pin routing. Fix: =options snd-hda-intel model=<quirk>= in =/etc/modprobe.d/=, reboot. [[https://bbs.archlinux.org/viewtopic.php?id=252295][arch 252295]]
+- Headphone path maps volume to the wrong control (yes). Headphone slider does nothing / headphones silent. The card-profile mixer path sets the Speaker element =volume = off=, breaking routing. Fix: edit =analog-output-headphones.conf=, change =volume = off= to =merge=, restart audio. [[https://bbs.archlinux.org/viewtopic.php?id=237456][arch 237456]]
+
+** PipeWire / WirePlumber routing
+
+- Default sink lands on HDMI instead of speakers (no). Boot with silence; playback goes to HDMI while speakers idle. WirePlumber auto-selects the HDMI node as default. Fix: =wpctl set-default <speaker-id>=. [[https://bbs.archlinux.org/viewtopic.php?id=309588][arch 309588]]
+- Default keeps reverting to the wrong sink (no). set-default holds until reboot, then flips back every session. Each sink's =priority.session= re-picks the wrong default. Fix: set =priority.session= per node in a WirePlumber rule, restart wireplumber. [[https://gist.github.com/DasBen/df9c2f6c18fff54a0ad6d19304915429][dasben gist]]
+- Sink suspended on idle, doesn't resume, and pops on start/stop (no). After a few seconds of silence the sink stays suspended; a loud pop/click and a delay when it wakes. =session.suspend-timeout-seconds= parks the node and the codec power-cycles. Fix: drop-in =session.suspend-timeout-seconds = 0=, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=264337][arch 264337]]
+- WirePlumber fails to start or a stale config jams routing (no; sudo if under /etc). Total silence; wpctl reports no sinks. The service crashes on a bad/incompatible config (user drop-in or a leftover =/etc/wireplumber/wireplumber.conf=). Fix: =journalctl --user -u wireplumber=, remove/move the offending config, restart. [[https://bbs.archlinux.org/viewtopic.php?id=294649][arch 294649]]
+- Corrupted WirePlumber restore state (no). No output after an update; sink present but never usable, or wrong routing persists. A corrupt =~/.local/state/wireplumber/= wedges default-node selection. Fix: =rm -rf ~/.local/state/wireplumber/=, restart pipewire pipewire-pulse wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=290825][arch 290825]]
+- pipewire-pulse dead, Pulse apps silent (no). Some apps play, but pactl/Pulse clients fail "Connection refused". The pipewire-pulse socket/service isn't running. Fix: =systemctl --user enable --now pipewire-pulse.socket pipewire-pulse.service=. [[https://bbs.archlinux.org/viewtopic.php?id=281062][arch 281062]]
+- Sink present but silent until a mute/unmute toggle (no). Correct default, un-suspended, but no sound until volume is touched or mute toggled. WirePlumber restores a muted / 0-volume state, or the node never opens until a mute change forces activation. Fix: =wpctl set-mute @DEFAULT_AUDIO_SINK@ 0= and =set-volume ... 1.0=. [[https://bbs.archlinux.org/viewtopic.php?id=300427][arch 300427]]
+
+** Bluetooth output
+
+- A2DP Sink profile deselects itself / unavailable (yes). A2DP switches back off when picked; only HSP/HFP shows. Stale pairing state in =/var/lib/bluetooth= from a PulseAudio-era config confuses bluez negotiation. Fix: stop bluetooth, remove/rename =/var/lib/bluetooth=, restart, re-pair. [[https://bbs.archlinux.org/viewtopic.php?id=280717][arch 280717]]
+- LDAC/aptX never negotiates, falls to SBC (no). Headphones connect but sound bad, stuck on SBC. Decoder libs absent, or =bluez5.codecs= order drops to baseline. Fix: install the codec packages, set =bluez5.codecs = [ ldac aptx_hd aptx aac sbc ]=, re-pair. [[https://bbs.archlinux.org/viewtopic.php?id=290413][arch 290413]]
+- Playback drops to HSP/HFP mid-song (no). Music goes mono/tinny when an app opens the mic. WirePlumber autoswitch-to-headset-profile fires on any input stream. Fix: =wpctl settings --save bluetooth.autoswitch-to-headset-profile false=; force =a2dp-sink=. [[https://wiki.archlinux.org/title/Bluetooth_headset][archwiki bt]]
+- BT sink not made default on connect (no). Headphones connect but audio keeps playing from laptop speakers. No switch-on-connect; the new sink's priority doesn't beat the built-in. Fix: =wpctl set-default <bt-sink-id>=, or a priority.session rule, or module-switch-on-connect. [[https://bbs.archlinux.org/viewtopic.php?id=304269][arch 304269]]
+- Silent sink after suspend/resume despite reconnect (no). After waking, headphones reconnect but running apps play no sound. The stream isn't re-initialized on the resumed sink; a seat-monitoring race. Fix: =monitor.bluez.seat-monitoring = disabled= drop-in; workaround =systemctl --user restart wireplumber pipewire=. [[https://forums.linuxmint.com/viewtopic.php?p=2781321][mint 2781321]]
+- Volume slider does nothing, absolute-volume conflict (no). OS volume has no effect on the headphones. PipeWire's absolute-volume passthrough hands volume to the device. Fix: =bluez5.enable-hw-volume = false= in a WirePlumber rule to restore software volume. [[https://wiki.debian.org/BluetoothUser/a2dp][debian a2dp]]
+- Adapter/dongle never exposes an audio sink (both). Dongle pairs but no A2DP sink; dmesg shows a firmware load failure. Controller firmware missing/outdated (e.g. MediaTek MT7921). Fix: install/update linux-firmware, reload btusb or reboot. [[https://bbs.archlinux.org/viewtopic.php?id=296026][arch 296026]]
+
+** HDMI / DisplayPort
+
+- GPU HDMI codec never initializes (both). No HDMI sink appears; aplay shows no HDMI device. The DSP/legacy driver-path selection is wrong so the HDMI codec is skipped. Fix: =options snd_intel_dspcfg dsp_driver=3=, rebuild initramfs. [[https://bbs.archlinux.org/viewtopic.php?id=290824][arch 290824]]
+- NVIDIA GPU audio removed by a runtime-PM udev rule (both). The NVIDIA HDMI card is missing or "inactive," only profile "off". An old NVIDIA runtime-PM udev rule powers down the audio function. Fix: comment out the audio-removal lines in the udev rule, reload/reboot. [[https://forums.developer.nvidia.com/t/no-audio-over-hdmi-linux-only/236341][nvidia 236341]]
+- NVIDIA HDMI audio needs DRM modesetting (both). Video works over HDMI, no audio sink. Without nvidia-drm modeset the HDMI audio function isn't exposed. Fix: =options nvidia_drm modeset=1=, rebuild initramfs. [[https://bbs.archlinux.org/viewtopic.php?id=264504][arch 264504]]
+- HDMI audio dies after suspend/resume, codec state (yes). Sound before suspend, silent after; dmesg "spurious response". The HD-Audio codec state isn't restored across resume. Fix: =sudo alsa force-reload= after resume, or =alsactl store=/=restore=. [[https://forums.developer.nvidia.com/t/nvidia-hdmi-audio-errors-after-resume-snd-hda-intel-spurious-response-last-cmd/149003][nvidia 149003]]
+- Empty ELD after resume marks the port disconnected (yes). HDMI port shows unavailable post-resume; WirePlumber logs "ELD info empty". A kernel regression fails to re-read the ELD on resume. Fix: boot linux-lts until fixed; replug the cable to force an ELD re-read. [[https://bbs.archlinux.org/viewtopic.php?id=306343][arch 306343]]
+- Wrong monitor is the audio sink, multi-monitor (no). Two displays on one GPU; audio goes to the wrong one. Only one HDMI/DP profile is active and the default picks the wrong port. Fix: =pactl set-card-profile <card> output:hdmi-stereo-extraN= for the right port. [[https://bbs.archlinux.org/viewtopic.php?id=295404][arch 295404]]
+- HDMI sink present but silent until daemon restart (no). HDMI profile selectable but no sound until PipeWire restarts. WirePlumber didn't pick up the sink on hotplug. Fix: =systemctl --user restart pipewire pipewire-pulse wireplumber=. [[https://bbs.archlinux.org/viewtopic.php?id=280352][arch 280352]]
+- HDMI sample-rate mismatch, display rejects the stream (no). HDMI audio crackles or drops on some content; the TV/monitor rejects non-48k rates. PipeWire negotiates a rate the display's ELD doesn't accept. Fix: pin the rate, =pw-metadata -n settings 0 clock.force-rate 48000= or set allowed-rates. [[https://bbs.archlinux.org/viewtopic.php?id=288932][arch 288932]]
+
+** USB DAC and hardware / BIOS
+
+- USB autosuspend powers the DAC down when idle (both). DAC plays, then silent after inactivity; sometimes needs a replug. The kernel autosuspends the port and severs the stream. Fix: =usbcore.autosuspend=-1=, or a udev rule setting =power/control=on=, or a silent keep-alive stream. [[https://destinmoulton.com/notes/howto/linux-usb-audio-keep-alive-service/][destinmoulton]]
+- USB DAC not auto-selected as default output (no). Sound keeps coming from onboard after the DAC is plugged in. WirePlumber gives the DAC an equal/lower node priority. Fix: a WirePlumber rule raising =priority.session=/=priority.driver= for the device, restart wireplumber. [[https://bbs.archlinux.org/viewtopic.php?id=290341][arch 290341]]
+- Kernel USB-audio regression, DAC has only an "Off" profile (both). After an upgrade the DAC (MOTU M4) enumerates but the only profile is "Off". A snd-usb-audio regression breaks stream setup for some devices. Fix: boot linux-lts or wait for the fixed kernel; downgrade as a stopgap. [[https://bbs.archlinux.org/viewtopic.php?id=279889][arch 279889]]
+- DAC needs an implicit-feedback quirk to sync (both). Playback stutters or drops to silence and won't recover; the device has no explicit feedback endpoint. snd-usb-audio doesn't apply generic implicit-feedback sync. Fix: =options snd_usb_audio implicit_fb=1= (or the per-device quirk_flags bit) in =/etc/modprobe.d/=. [[https://lkml.iu.edu/hypermail/linux/kernel/2206.0/08494.html][lkml usb-audio]]
+- Headphone jack not detected, speakers keep playing (both). Plugging headphones doesn't mute the speakers; no auto-switch on insert. The HDA auto-parser picks the wrong model so jack events aren't wired to the switch. Fix: =options snd-hda-intel model=<board>= in =/etc/modprobe.d/=, reboot. [[https://bbs.archlinux.org/viewtopic.php?id=265363][arch 265363]]
+- Front-panel headphone jack not wired by BIOS pin config (both). The front jack produces nothing and never appears; rear jacks work. The BIOS marks that codec pin "not connected". Fix: =hdajackretask= override the pin to Headphone/Line-out, install the boot override, reboot. [[https://github.com/alsa-project/alsa-tools/blob/master/hdajackretask/README][hdajackretask]]
+- BIOS-disabled onboard audio, or a GPU HDA controller hides it (both). No card detected (empty =aplay -l=), or only the GPU/HDMI device appears. Onboard audio is disabled in BIOS, or the GPU's HDA controller takes over ordering. Fix: re-enable onboard audio in BIOS; =options snd-hda-intel enable=1,0= to disable the GPU's audio function. [[https://bbs.archlinux.org/viewtopic.php?id=221296][arch 221296]]
+
+** Application / browser / sandbox
+
+- Flatpak app has no PulseAudio socket (no). A Flatpak app is silent while native apps play. The manifest was built without =--socket=pulseaudio=. Fix: =flatpak override --user --socket=pulseaudio <app>=. [[https://github.com/flatpak/flatpak/issues/878][flatpak 878]]
+- Flatpak silent on a PipeWire-only system (no). App with pulse permission still has no sound on pure PipeWire. Flatpak has no native PipeWire socket permission. Fix: =flatpak override --user --filesystem=xdg-run/pipewire-0 <app>=. [[https://github.com/flathub/com.valvesoftware.Steam/issues/1451][flathub steam 1451]]
+- Snap app can't play, audio-playback interface unconnected (no). A snap (often =--dangerous=) produces no sound. Locally-installed snaps skip the auto-connect assertion. Fix: =snap connect <snap>:audio-playback=. [[https://bugzilla.mozilla.org/show_bug.cgi?id=1685284][mozilla 1685284]]
+- Browser per-tab mute zeroes the app stream (no). Firefox/Chrome plays nothing; the app stream shows muted, device fine. A tab was muted, muting the per-stream sink-input. Fix: Unmute Tab, or un-mute the app's stream in pavucontrol. [[https://bbs.archlinux.org/viewtopic.php?id=275694][arch 275694]]
+- Wine/Proton game silent, wrong audio driver (no; sudo for 32-bit libs). A Wine/Proton game has no output. The Wine driver is set wrong, or 32-bit audio libs are missing. Fix: winecfg output device to System default; install =lib32-libpulse= / =lib32-pipewire=. [[https://bbs.archlinux.org/viewtopic.php?id=135032][arch 135032]]
+- App hard-coded to raw hw:0, device busy (no). MPD/shairport errors "Device or resource busy" and stays silent, blocking others. The app points at raw =hw:0=, grabbing the card exclusively. Fix: change the app's device to =default= or =plughw=; =fuser -v /dev/snd/*= to find the holder. [[https://community.volumio.com/t/fix-mpd-failed-to-open-alsa-device-hw-0-0-device-busy/686][volumio mpd]]
+- Chromium doesn't follow the default-sink change (no). After switching the default output, Chrome keeps playing to the old sink. Chromium latches its stream to the start-time sink. Fix: reassign the Chromium stream in pavucontrol; PipeWire remembers it. [[https://bbs.archlinux.org/viewtopic.php?id=116888][arch 116888]]
+- Electron app routed to the wrong sink (no). Discord is silent while YouTube works; its stream went elsewhere. Electron apps share a generic stream name so a prior routing rule misdirects it. Fix: move the app's stream to the right sink in pavucontrol while it plays. [[https://bbs.archlinux.org/viewtopic.php?id=277447][arch 277447]]
+
+** Audio quality (crackle, xruns, latency)
+
+- Quantum drops too low under load (no). Crackling/popping that worsens under CPU load. PipeWire's dynamic quantum negotiates a buffer that underruns the sink. Fix: =default.clock.min-quantum = 1024= (raise as needed) in a pipewire.conf.d drop-in, restart pipewire. [[https://bbs.archlinux.org/viewtopic.php?id=303024][arch 303024]]
+- Realtime scheduling denied, RTKit (yes). Xruns/dropouts uncorrelated with CPU load; the audio thread misses deadlines. PipeWire can't get SCHED_FIFO (RTKit unavailable or capped). Fix: rtkit-daemon running, user in =realtime=, =/etc/security/limits.d/= granting rtprio + memlock; re-login. [[https://bbs.archlinux.org/viewtopic.php?id=283334][arch 283334]]
+- Timer-based scheduling on a fussy USB DAC (no). Periodic crackle on a USB interface. tsched mis-estimates the batch USB device's buffer position. Fix: a WirePlumber ALSA rule with =api.alsa.disable-tsched = true= and a modest headroom, or the Pro Audio profile. [[https://bbs.archlinux.org/viewtopic.php?id=284888][arch 284888]]
+- Forced global sample rate causes resample artifacts (no). Distortion on 44.1k content, or a stream stuck upsampling; also seen on USB DACs that only accept a limited rate set. A hard =default.clock.rate= forces everything through the resampler. Fix: set =default.clock.allowed-rates= to a list so the device follows the source, restart pipewire. [[https://bbs.archlinux.org/viewtopic.php?id=288932][arch 288932]]
+- Small quantum fine for music, too tight for browser/games (no). Audio crackles only in Chrome/Firefox or games, clean elsewhere. The heavy client can't keep the small global quantum fed. Fix: launch with =PIPEWIRE_LATENCY=2048/48000=, or a WirePlumber stream rule setting =node.latency= for that app. [[https://forum.endeavouros.com/t/pipewire-guide-audio-crackling-popping-and-latency/69602][endeavour 69602]]
+- HDA codec power-save clicks and BT-latency hits (yes). Loud click/pop on first play after idle on internal HDA; also wrecks Bluetooth latency. =snd_hda_intel power_save= cuts codec power and clicks on wake. Fix: =options snd_hda_intel power_save=0 power_save_controller=N= in =/etc/modprobe.d/=. [[https://forums.linuxmint.com/viewtopic.php?t=186531][mint 186531]]
+- Insufficient ALSA headroom on an emulated/quirky device (no). Constant fine crackle from a sink whose hardware pointer PipeWire can't track (VM audio, cheap onboard). The default small =api.alsa.headroom= leaves no slack. Fix: a WirePlumber ALSA rule adding =api.alsa.headroom = 2048=. [[https://pipewire.pages.freedesktop.org/wireplumber/daemon/configuration/alsa.html][wp alsa config]]
+
+* Sources
+
+Every entry carries its source inline as an org link. Reports span the Arch/Manjaro/EndeavourOS/Fedora/Ubuntu/Mint/openSUSE forums, askubuntu, the PipeWire and WirePlumber docs, ALSA and Flatpak issue trackers, kernel bug trackers, and vendor forums (NVIDIA, Dell). Collected 2026-07-10.
+
+* Sources
+
+(collected per entry)