Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

so this may not directly related to surface thing but alsa config or realtek codec or hw compat
I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
and that also appiled on Pulseaudio

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
/ and that also appiled on Pulseaudio

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
/ last but not least; I recommended to solve this problem by using sample_rate and bit_depth that allowed in Windows, if combination not possible then try another settings that have better sound quality.

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem. So this also conclude that put lid down just hide poor thing but the sound still poor just more diffcult to hear.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
/ last but not least; I recommended to solve this problem by using sample_rate and bit_depth that allowed in Windows, if combination not possible then try another settings that have better sound quality.

PS1: breif test on my hw:0,0 only support 16bit/32bit (yeah it is normal that ALSA support config is not same as on Windows) at 44.1/48khz, I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
PS4: /proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.
PS5: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

[PCM codec report]
[Test Result]
SurfaceKernel+16bit/44.1khz: N/A

PS1: breif test on my hw:0,0 only support 16bit/32bit (yeah it is normal that ALSA support config is not same as on Windows) at 44.1/48khz, I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
PS4: /proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.
PS5: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

[PCM codec report]
[Test Result]

24bit or 96khz are not supported by alsa HW direct

SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: N/A
SurfaceKernel+32bit/48khz: N/A
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: breif test on my hw:0,0 only support 16bit/32bit (yeah it is normal that ALSA support config is not same as on Windows) at 44.1/48khz, I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
PS4: /proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.
PS5: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report

Test Result

// 24bit or 96khz are not supported by alsa HW direct
SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: N/A
SurfaceKernel+32bit/48khz: N/A
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: breif test on my hw:0,0 only support 16bit/32bit (yeah it is normal that ALSA support config is not same as on Windows) at 44.1/48khz, I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
PS4: /proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.
PS5: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report

Test Result

// 24bit or 96khz are not supported by alsa HW direct
SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: Poor sound
SurfaceKernel+32bit/48khz: Normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: breif test on my hw:0,0 only support 16bit/32bit (yeah it is normal that ALSA support config is not same as on Windows) at 44.1/48khz, I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
PS5: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report

/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit or 96khz are not supported by alsa HW direct
SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: Poor sound
SurfaceKernel+32bit/48khz: Normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: Poor sound
SurfaceKernel+32bit/48khz: Normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem. So this also conclude that put lid down just hide poor thing but the sound still poor just more diffcult to hear.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
/ so the solution may be: using sample_rate and bit_depth that allowed in Windows, if combination not possible then try another settings that have better sound quality.
/ I hope someone see similar problem can got solved using my recommendation

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for test have best-method resampled, to it should sound good in everycases
SurfaceKernel+16bit/44.1khz: PoorSound
SurfaceKernel+16bit/48khz: Normal
SurfaceKernel+32bit/44.1khz: Poor sound
SurfaceKernel+32bit/48khz: Normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for tested is best-method resampled.
SurfaceKernel+16bit/44.1khz: N/A
SurfaceKernel+16bit/48khz: N/A
SurfaceKernel+32bit/44.1khz: Poor sound
SurfaceKernel+32bit/48khz: Normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for tested is best-method resampled.
SurfaceKernel+16/32bit/44.1khz: poor sound
SurfaceKernel+16/32bit/48khz: normal
GenericKernel+16bit/44.1khz: N/A
GenericKernel+16bit/48khz: N/A
GenericKernel+32bit/44.1khz: N/A
GenericKernel+32bit/48khz: N/A

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit at 48 while headphone support both 16/24bit
/proc/asound/card0/codec#0 reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for tested is best-method resampled.
BothGenericAndSurfaceKernel + 16/32bit + 44.1khz: poor sound
BothGenericAndSurfaceKernel + 16/32bit + 48khz: normal

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit 48khz while headphone support both 16/24bit but only 48khz
/proc/asound/card0/codec#0 (idk if I interpret it wrong or not) reported speaker actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for tested is best-method resampled.
BothGenericAndSurfaceKernel + 16/32bit + 44.1khz: poor sound
BothGenericAndSurfaceKernel + 16/32bit + 48khz: normal

PS1: I only tested for 32bit on both freq, I will further report testing in this msg.
PS2: https://stackoverflow.com/questions/31060717/wav-files-at-any-rate-except-44-1khz-have-messed-up-sound idk if this relate
PS3: Haven't retest if this also happen on headphone but as I breifly test it sound like normal

PCM codec report on Linux and other info

On Windows, speaker only support 16bit 48khz while headphone support both 16/24bit but only 48khz
/proc/asound/card0/codec#0 (idk if I interpret it wrong or not) reported that speaker/headphone actually supported 44100/48000 at 16/20/24bit which these all combination is supported in default PCM reported by given file.

Test Result

// 24bit (yeah it is normal that ALSA support config is not same as on Windows) or 96khz are not supported by alsa HW direct
// Sound used for tested is best-method resampled.
BothGenericAndSurfaceKernel + 16/32bit + 44.1khz: poor sound
BothGenericAndSurfaceKernel + 16/32bit + 48khz: normal

Ok I have rearranged so it easier to read
first I have to say that my latest test conclude that lid state in Windows not affect into poor sound just little charecteristic. That mean lid positioning is not related to the problem. So this also conclude that put lid down just hide poor thing but the sound still poor just more diffcult to hear.

I now got solution, the problem is about ALSA or realtek codec driver
but what most surprise is what to say:

• using ALSA hw:0,0 (which is Realtek codec that play on laptop speaker) @32bit/48000Hz it sound normal (even no optimization based on tablet/stage/laptop mode)
• testing same but 44100Hz it sound poor
• As brief test, this also happens on Pulseaudio in the same way

/ so this may not directly related to surface thing but alsa config or realtek codec or hw compat
/ I think there are ones having similar issues like me on non-surface device, but I took much time for me to search it, but I see one that searched, see PS2.
/ I will try test on 16bit and generic kernel also, at least HW direct of 32bit 48khz sound good on surface kernel
/ so the solution may be: using sample_rate and bit_depth that allowed in Windows, if combination not possible then try another settings that have better sound quality. However on SLS set Pulseaudio/ALSA to use 48000Hz for speaker. on my settings set both samplerate and alternative_samplerate PulseAudio settings to 48000, that prevent application from requesting 44.1khz rate and create problem.
/ I hope someone see similar problem can got solved using my recommendation

In reply to @qzed:matrix.org
IIRC there are some older issues about sound and eq-tuning somewhere, so maybe a device-independent wiki page for that would be great

thanks for suggestion
however I think my idea is to put "48000hz SLS problem fix " into SLS device wiki page at first place maybe.
however if there are many devices got similar problem then maybe I think it should be at section "post-installation" of page "Installation" instead.

And my testing infomation feel free to copied yeah, however I will copied into my github repo when I have my freetime thanks.

PS: I'm not native english, sorry if I using wrong wording :)