Help me understand no Surround Sound Profile

Help
1

I had this problem b4 under Arch, I somehow fixed it without really understanding what I actually did.

I really want to understand it this time and make it right:

I have Pipewire enabled as it is now default.

  services.pipewire = {
    enable = true;
    pulse.enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
  };

I also have a onboard Starship/Matisse HD Audio.

Problem:

There is no 5.1 Profile in pavuctl to be selected, only Duplex Stereo.
If I go to alsamixer and then select the Starship/Matisse HD device I can see that it is configured to have 2ch, i can then change that to 6ch but that still doesn’t make another profile available in pavuctl.

Under Arch after a reboot for some magic reason 5.1 Profile appeared after that but not this time. And as written, I absolutely had no clue why it suddenly worked.

Question:
How to properly configure the different layers of the pipewire/alsa sound architecture to enable a 5.1 Surround sound profile?

2

The following is also not working at all

  services.pipewire = {
    enable = true;
    pulse.enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    wireplumber.configPackages = [
      (pkgs.writeTextDir "share/wireplumber/main.lua.d/51-change-channels.lua" ''
        alsa_monitor.rules = {
          {
            matches = {{{ "alsa.card_name", "matches", "HD-Audio Generic*" }}};
            apply_properties = {
              ["audio.channels"] = "6",
              ["audio.position"] = "FL,FR,RL,RR,FC,LFE",
            },
          },
        }
      '')
    ];
  };

Why, cause when I change the number of channels via alsamixer and then restart wireplumber I get a completely different node with different name and device id and that one already has the settings set correctly.

But the original node can not be changed to 6 channels via wireplumber (I assume thats also the reason, why pavuctl isn’t able to select any 5.1 profile cause the node has only 2 channels)

How can I do what I do can do with alsamixer (changing channels to 6) on bootup before wireplumber even starts up?