Connect the Stereodrome viewer to a computer via USB. Run the software application and play your music. Best experienced when using headphones.

There is a 64-bit standalone application for Mac OS X/MacOS.
If you instead wish to control your Stereodrome USB from Pure Data, then use the Pd patch.

Pure Data, or Pd, is an open source visual programming environment for audio analysis, synthesis, and processing, with a rich set of multimedia capabilities. Available for Mac OS X, Windows, Debian GNU/Linux.
A manual can be found at: http://msp.ucsd.edu/Pd_documentation/index.htm

You can install Pure Data from https://puredata.info/downloads/pure-data
When installed, go to Help/Find Externals.
Search for the 'comport' and 'else' libraries and install those.
Objects from these libraries are required to run the Stereodrome patch.

Stereodrome for Mac OS X:

The speaker icon in the middle is the on/off switch.
Selecting system mode will activate an external input and de-activate the player.

When generating or editing your own audio in other software, channel your sound to a virtual output and through the app to the real output of your choice.
There are several virtual soundcard applications out there. For OS X, Soundflower is free and easy to use.

Soundflower is a free Mac OS X (10.2 and later) system extension that allows applications to pass audio to other applications. Soundflower presents itself as an audio device, allowing any audio application to send and receive audio with no other support needed. Soundflower is hosted on Github.