[BUG] XPS 9710 no Headphones Audio Output

### Pre-flight checklist

- [x] I have searched existing issues and this is not a duplicate.
- [x] I have read the [Contributing Guidelines](https://github.com/CachyOS/linux-cachyos/blob/master/CONTRIBUTING.md).
- [x] I have verified the issue is reproducible with the latest available CachyOS kernel.
- [x] I have tried to reproduce the issue on Arch Linux's `linux` kernel.

### Upstream / vanilla kernel check

I have not tested with a vanilla/upstream kernel

### Kernel variant

linux-cachyos (EEVDF, Clang)

### System information (cachyos-bugreport.sh)

```text
https://paste.cachyos.org/p/0439a8a.log
```

### Manual system information (if cachyos-bugreport.sh is unavailable)

```text
https://paste.cachyos.org/p/0439a8a.log
```

### Bug description

Dell XPS 17 9710 (Tiger Lake, Realtek RT711SoundWire)** headphone issue.

# Initial symptoms

* ✅ Internal speakers worked.
* ❌ 3.5 mm headphone jack produced no sound.
* ✅ The headphones worked perfectly when connected to the Dell D3100 USB dock.
* PipeWire detected the headphone device correctly.
* Switching between Speaker and Headphones worked.
* Applications were routed to the correct sink.

Machine:
Dell XPS 17 9710
BIOS:1.39.0

Kernel (tested):
linux-cachyos
7.1.3
7.1.4
linux-cachyos-lts
6.18

Audio controller:
Intel 500 Series HD Audio 8086:43c8

Driver initially: sof-audio-pci-intel-tgl
Later after forcing legacy HDA: snd_hda_intel but it removed all audio outputs

# ALSA devices
Originally:sofsoundwire
containing

* Speaker
* Headphones
* HDMI outputs

Everything looked correct.

# PipeWire
Detected correctly:
500 Series HD Audio Headphones and streams were attached correctly.

Example:
Brave
output_FL -> Headphones
output_FR -> Headphones

So PipeWire routing is NOT the problem.

# Symptoms

When selecting Headphones:

* absolutely no sound
* touching the volume slider caused

click
pop

inside headphones.

That is extremely important.

It means

* codec wakes up
* amplifier receives power
* jack is physically connected

but audio path never opens.

# alsamixer

Inspected card:
sofsoundwire

Headphone control:
Headphone
showed

00
```

No volume.

# Kernel logs
No failures.

Topology loaded: sof-tgl-rt711-rt1308-rt715.tplg

Firmware:
intel/sof/sof-tgl-h.ri loaded correctly.

No

* timeout
* codec error
* firmware crash
* probe failure

# SOF firmware

Installed:

sof-firmware
2025.12.2

# I suspected

Possible regression in

* SOF
* SoundWire
* RT711 routing

because everything appears functional except analogue playback.

# Tried legacy HDA

Created modprobe option forcing

snd_hda_intel

instead of SOF. After rebuilding initramfs and rebooting: Driver changed from sof-audio-pci-intel-tgl to snd_hda_intel

# Result was bad. The analogue devices disappeared. Now

aplay -l

only showed

* Intel HDMI
* NVIDIA HDMI
* Dell Dock USB

No speakers.

No headphones.

So the XPS 9710 clearly **requires SoundWire/SOF**.

I reverted that idea.

# No evidence of

* PipeWire bug
* WirePlumber bug
* Wrong default sink
* Wrong application routing
* Muted output
* Missing firmware
* Codec probe failure
* Jack detection failure

# What strongly points to

Most likely one of:

1. SOF regression
2. SoundWire routing bug
3. RT711 codec bug
4. Dell XPS 9710 quirk missing in newer kernels

# What I have NOT yet tried

## 1. Boot an older kernel

For example:
arch-linux

If headphones work there, it's almost certainly a kernel regression.

## 2. Test Ubuntu Live USB

Boot Ubuntu 24.04/24.10 **without installing**.

If headphones work there:

* hardware is fine
* Arch/CachyOS stack is the issue.

If they also fail:

* firmware/BIOS/kernel quirk.

## 3. Force UCM profile

Sometimes WirePlumber chooses the wrong UCM profile. Worth checking.

## 4. Compare with another XPS 9710 to see whether other users on recent kernels have the same issue.

Specifically:
Dell XPS 9710
RT711
RT1308
RT715

### Steps to reproduce

1. Install CachyOS
2. Boot
3. Set all sound outputs to headphones
4. Listen to something

### Expected behavior

To hear sound trough the headphones

### Actual behavior

Click/pops,

### Logs / stack traces

```text

```

### Additional system information

provided in the log