In reply to @mindtree:matrix.org
Does anyone happen to be both successfully using flakes for their NixOS configuration and have audio plugins working in their DAW?

In reply to @Minijackson:matrix.org
do you have the value of your e.g. $LV2_PATH?

$ echo $LV2_PATH 
/home/mindtree/.lv2:/home/mindtree/.nix-profile/lib/lv2:/run/current-system/sw/lib/lv2

In reply to @Minijackson:matrix.org
IIRC, this means that your plugins installed through users.users.mindtree.packages won't be found, since you don't have the path /etc/profiles/per-user/$USER/lib/lv2

which gives:

github:musnix/musnix/6eb5c1714fbb7622b7270be78243365f9c55c9cb
├───nixosModule: NixOS module
└───nixosModules
    └───musnix: NixOS module

{
  description = "...";

  inputs.nixpkgs.url = "...";
  inputs.musnix.url = "github:musnix/musnix";

  outputs = { self, nixpkgs, musnix }: {
    nixosConfigurations."myConfig" = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";

      modules = [
        musnix.nixosModules.musnix
        # ...
      ];
    };
  };
}