A test head assembly can include a probe card, which can include first contact areas. The test head assembly can also include a contactor, which can include second contact areas. An interposer can include first spring contact structures and second spring contact structures. The first spring contact structures can contact one of the first contact areas, and the second spring contact structures can contact one of the second contact areas. Ones of the first spring contact structures can be electrically connected through the interposer to ones of the second spring contact structures. One of the first spring contact structures can include a pair of contacts, both of which can extend from a first surface of the interposer to contact one of the first contact areas. Alternatively or additionally, one of the second spring contact structures can include a pair of contacts, both of which can extend form a second surface of the interposer to contact one of the second contact areas.