To generate loud signals humans already used horns as "amplifiers" in ancient times.

This concept follows the principle of the classic gramophone. You just plug your earphones in the cavity at the back of the
horn. The geometry of the horn boosts the earphones to a volume that is suitable for a livingroom.
Calculated by a mathematic formula the horn is optimized in size and form for inear-headphones.

Technical details:

to be announced when product is available