Headphones vs Speakers for Brainwave Audio
Quick answer: Headphones provide stronger left/right channel separation; speakers provide more environmental awareness and may be adequate for non-binaural recordings.
Headphones
Best suited when a recording depends on separate signals delivered to each ear. Noise isolation can also make lower volume levels more practical in noisy environments.
Speakers
Useful for ambient tracks or pulsed tones that do not require strict ear-specific delivery. They may also be more comfortable for some listeners.
Follow the recording instructions
There is no universal rule for every brainwave-style audio product. Use the method the seller specifies and keep volume comfortable.