We describe a single-axis haptic interface which is based on a dual-stage actuator technique and which is aimed at achieving perfect transparency to a human user. The paper shows how all parasitic forces arising from inertia and friction can be brought below human detection thresholds, yet, the system is able to output significant torque. It has a stage with a large motor coupled to a distal stage with a smaller motor via a viscous coupler based on the principle of eddy current induction. The paper also describes its control principle and preliminary results.