This is for a Sony Vaio laptop, marked:

PCG-7K1L
VGN-FJ290

The default Debian Jessie + Mate configuration for this guy's sound-card is such that the only place one can get sound-output is through the A/V output connector. Not through the speakers, not through the headphone-jack.

(Interestingly, I didn't realize this was an A/V connector... I thought it was a line-out jack... BUT, it only output audio on the left channel, and sometimes the right channel would be noise, sounding a bit like 60Hz)

But I wanted left/right, and speakers would be nice... so I did some searching.

Most results said I need to recompile the kernel, some said you need to do some really gnarly stuff with alsa... But this is an old system, surely linux support for it should've been somewhat functional for some time...

Finally I came across:

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1562396

Which, if you scroll to the bottom describes the utility: "hdajackretask"

Turns out, the only problem is that the BIOS isn't reporting (or the system isn't detecting) the output-mapping correctly.

So, run "hdajackretask" and change "Pin 0x10" to "Line Out"

Note that it does NOT work to change it to "Internal Speaker"

Here are my notes:

# Realtek ALC260

# DEFAULTS:
#  0x0f    "Green Headphone, Rear side"     -> Headphone
#  0x10    "Internal Line Out, Mobile-In"   -> <not selected>
#  0x12    "Pink Mic, Rear side"            -> Microphone
#  0x13    "Internal Mic, Mobile-In"        -> Internal mic
# PHYSICALLY:
#  Yellow   (Composite?!)
#  Red      Mic-in
#  Black    Headphones
#
# Default settings results in sound ONLY going to yellow jack!
#  (Left-headphone only)
#  (Often results in noise, 60Hz-ish, on right)

# OVERRIDE ATTEMPTS:
#  0x10     -> "Headphone" -> Speakers + Yellow getting output
#           -> "Internal Speaker" -> Yellow only
#           -> "Internal Speaker (LFE)" -> Same
#           -> "Internal Speaker (Back)" -> Same
#                vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#           -> "Line out (Front)
#                    Speakers + Yellow
#                    Headphone (Black) Overrides Speakers
#                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# BEWARE:
#  Mate's Sound Preferences
#    -> Hardware
#    -> Test Speakers
#        NO EFFECT with Tests....