General MIDI Player 2.2.4 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this Mac application is Defective Records Software. The application is included in Audio & Video Tools. We recommend checking the downloaded files with any free antivirus.
From the developer:
This app is a tool that allows you to turn your Mac into an instrument, using its built-in General MIDI support. You can play those instruments using either your mouse, computer keyboard (including support for non-US keyboards), or MIDI device (both hardware and software MIDI devices supported). It has a simple, one-screen interface, that will let you start making music with your favorite General MIDI instrument in seconds.
You may want to check out more Mac applications, such as Sweet MIDI Player, MIDI Player - Modify Music or MIDI Player & Converter, which might be related to General MIDI Player.