0.78 mm 2-Pin — Universal IEM Connector

Two parallel 0.78 mm-diameter cylindrical pins spaced 2 mm apart, friction-retained by the IEM-side socket — the simplest possible mechanically-detachable IEM connector. Polarity is fixed by socket geometry; the cable termination is keyed so the channel and phase can’t be reversed.

Has progressively displaced MMCX as the dominant IEM termination since around 2018. Two reasons: the rigid pin-and-socket design doesn’t loosen the way MMCX retention beads do, and the pin geometry is mechanically simpler to manufacture to consistent tolerances across the price spectrum from $30 IEMs to $4000 flagships.

Used by the reference dynamic IEM, the tribrid hybrid IEM (alongside Pentaconn Ear on some variants), and the planar IEM. Cable: OCC copper IEM cable terminates in this connector by default.