anchor.diff:      };
   
     nodes =
  -    { client = 
  +    { client =
         { ... }: { };
   
         serverALSA =
  -        { ... }: (mkServer {
  -          mpd = defaultMpdCfg // {
  -            network.listenAddress = "any";
  -            extraConfig = ''
  -              audio_output {
  -                type "alsa"
  -                name "ALSA"
  -                mixer_type "null"
  -              }
  -            '';
  -          };
  -
  -          musicService = with defaultMpdCfg; musicService { inherit user group musicDirectory; };
  -        }) // { networking.firewall.allowedTCPPorts = [ 6600 ]; };
  +        { ... }: lib.mkMerge [
  +          (mkServer {
  +            mpd = defaultMpdCfg // {
  +              network.listenAddress = "any";
  +              extraConfig = ''
  +                audio_output {
  +                  type "alsa"
  +                  name "ALSA"
  +                  mixer_type "null"
  +                }
  +              '';
  +            };
  +            musicService = with defaultMpdCfg; musicService { inherit user group musicDirectory; };
  +          })
  +          { networking.firewall.allowedTCPPorts = [ 6600 ]; }
  +        ];
   
         serverPulseAudio =
  -        { ... }: (mkServer {
  -          mpd = defaultMpdCfg // {
  -            extraConfig = ''
  -              audio_output {
  -                type "pulse"
  -                name "The Pulse"
  -              }
  -            '';
  -          };
  +        { ... }: lib.mkMerge [
  +          (mkServer {
  +            mpd = defaultMpdCfg // {
  +              extraConfig = ''
  +                audio_output {
  +                  type "pulse"
  +                  name "The Pulse"
  +                }
  +              '';
  +            };
   
  -          musicService = with defaultCfg; musicService { inherit user group musicDirectory; };
  -        }) // { hardware.pulseaudio.enable = true; };
  +            musicService = with defaultCfg; musicService { inherit user group musicDirectory; };
  +          })
  +          {
  +            hardware.pulseaudio = {
  +              enable = true;
  +              systemWide = true;
  +              tcp.enable = true;
  +              tcp.anonymousClients.allowAll = true;
  +            };
  +            systemd.services.mpd.environment.PULSE_SERVER = "localhost";
  +          }
  +        ];
       };
   
     testScript = ''
  
positive.code:     play_some_music($serverALSA);
      play_some_music($serverPulseAudio);
  
      $client->succeed("$mpc -h serverALSA status");
  
      # The PulseAudio-based server is configured not to accept external client connections
  
negative.code: import ./make-test.nix ({ pkgs, lib, ... }:
    let
      track = pkgs.fetchurl {
        # Sourced from http://freemusicarchive.org/music/Blue_Wave_Theory/Surf_Music_Month_Challenge/Skyhawk_Beach_fade_in
  