Plexamp is a small music player with a number of unique features. The most classic and beloved small audio player, Winamp, was first released almost exactly TWENTY years ago. Written in a low-level language, it ran on Windows and was limited to playing files on the local (or networked) filesystem. Plex, on the other hand, provides a best-in-class client/server model, an extremely metadata rich library, is highly portable, and gives you access to your entire music collection from anywhere in the world; the need was to pair this with a similarly excellent music player. Runs on macOS and Windows, and works like a native app (e.g. media keys for skipping tracks and toggling play/pause are supported, as are notifications). Direct plays just about any music format you could dream of throwing at it. It can be used to remote control other Plex players and can be remote controlled itself.
Works in offline scenarios (e.g. on an airplane with a server running on a laptop, or on your private submarine).
Besides support for standard media keys, it offers a global activation hotkey much like Spotlight on macOS (cmd+shift+space). This makes it quicker than ever to find something in your music library. There are a number of additional nice keybindings for power users. You can download Plexamp on the Plex Labs page.