Earphones are becoming very sophisticated and costly.

Ultimate Ears of Logitech have launched 'Ultimate Ears 18 Pro'
It has 2 high frequency, 2 mid range and 2 Low frequency drivers for each ears. That's a total of 6 drivers !
Also each driver has it's own channel and passive crossovers.

Those who have a locker full of money can buy it for $1350.