OP here. I built this engine because I realized auditory entrainment (for focus and my own Aphantasia) is often compromised by standard streaming platforms.

Most codecs (MP3/AAC) use "Joint Stereo" (Mid/Side coding) to save bandwidth. Since binaural beats rely entirely on the subtle phase difference between Left/ Right channels, compression algorithms tend to treat that data as redundant and smooth it over.

I didn't want to leave it to chance, so I moved the stack to the Web Audio API. It generates the sine waves in real-time (client-side), ensuring mathematical precision and perfect channel isolation.

Happy to answer questions about the physics or implementation.