An electrical connector system includes mating pin and socket connectors each designed for increased contact density to improve performance of high-speed data transfer. The connectors include features for retaining a plurality of pin or socket contacts in a ganged, co-aligned configuration and for shielding groups of contacts from one another to reduce interference and crosstalk. The connectors further include features for providing strain relief to the internal wires and/or cables. One of the connectors may include a plug insert with cantilevered fingers extending therefrom that contact a conductive surface of the mating connector to provide a mechanical connection and a low-impedance pathway between the mating connectors for grounding and shielding. The connectors are designed to be readily assembled and disassembled for repair or rework without the use of special tools.