anchor.diff:          '';
         };
   
  +      extraConfig = mkOption {
  +        type = types.lines;
  +        default = '''';
  +        example = ''
  +          defaults.pcm.!card 3
  +        '';
  +        description = ''
  +          Set addition configuration for system-wide alsa.
  +        '';
  +      };
  +
       };
   
     };
  
positive.code:   config = mkIf config.sound.enable {
  
      environment.systemPackages = [ alsaUtils ];
  
      # ALSA provides a udev rule for restoring volume settings.
      services.udev.packages = [ alsaUtils ];
  
negative.code:   inherit (pkgs) alsaUtils;
  
    soundState = "/var/lib/alsa/asound.state";
  
    configPaht = "asound.conf";
  
  in
  
  