TwinACStacks
Headphoneus Supremus
It largely depends on what the crossover points are and if there is overlap for a continuous soundwave. In ear is even trickier because of the way you hear. We always hear of neutral or balnced earphone EQ. This is actually false. High frequecy waves travel faster than low frequecy and so on.... A perfectly flat frequency response that close to ypue eardrum frankly wouls sound like dookie. The frequency patterns on IEMs are highly engineered to sound pleasing and with crossovers are purposely overlaped so there isn't any gaps in the audio signal as it is divied up between drivers.
TWIN
TWIN