For Mac App Store users, you will find Boom 3D window on launch, here you will find a text mentioning "Drag and drop a song to play”. (Please refer screenshot below)
Once you drag and drop a song with the format provided, the Boom 3D player activates for that particular song.
To enable system wide audio enhancement, click on the "Experience More" button (please refer screenshot), you will be directed to download an audio component.
Download and install the Boom 3D audio component and restart your Mac.
Once installed, you can make use of System Wide EQ, Volume Boosting and 3D functionality options.