windows 7 – No audio from S/PDIF optical output on Realtek ALC1200 onboard audio (MSI B550 motherboard)

I have an MSI B550M Mortar motherboard which has Realtek ALC1200 onboard audio. Currently running Windows 7 x64.

I’m trying to use the S/PDIF optical output with Logitech speakers but I’m not getting any sound output at all no matter what formats I test, or what settings I apply.

Additionally, I only see options for 2 channel output formats whereas there should be 5.1 channel options to chose from, too.

The speakers and optical cable are confirmed working with my old motherboard’s onboard audio.

The Hardware Ids of the MSI B550M’s ALC1200 audio device are:

HDAUDIOFUNC_01&VEN_10EC&DEV_0B00&SUBSYS_1462EC94&REV_1000
HDAUDIOFUNC_01&VEN_10EC&DEV_0B00&SUBSYS_1462EC94

Things I have already tried:

  • Latest “Univeral” Realtek audio drivers from their site (R2.82)

  • Older Realtek drivers which worked with an Asus motherboard (R2.80)

  • Drivers from a different MSI motherboard with similar onboard audio for Windows 7 (driver v6.0.1.8619)

  • Drivers from a totally different mobo (Asrock) which uses the same chip as mine (driver v6.0.9132.1)

    N.B. in this case, the driver package contains the exact same hardware ID string as mine so it should definitely be compatible

An extremely helpful driver modder has been trying to help me on a Techpowerup forum thread but so far I’ve had no success.

Any suggestions are very welcome.