An electrical connector system (10) includes a backplane connector (12) and a daughtercard connector 14 coupled to the backplane connector. The backplane connector includes a housing (200) holding a plurality of backplane contact assemblies (20) that are movable relative to the housing and each have a center contact (250) and an outer shell (240) surrounding the center contact configured to be terminated to coaxial cables. The daughtercard connector includes a housing (100) holding a plurality of daughtercard contact assemblies (102) coupled to corresponding backplane contact assemblies. The daughtercard contact assemblies are configured to be directly terminated to a daughtercard circuit board (18).