The present investigation focuses on the output energy control of the nonlinear sine-Gordon model in a practical situation where only spatially sampled sensing and actuation are available. The speed-gradient method that has corroborated its utility for the sine-Gordon model, controlled through the manipulable parameters of the external field and boundary actuation, is now generalized to the spatially sampled sensing and actuation, aiming to pump/dissipate the energy of the model to a desired level. Luenberger-type observers are additionally developed in the present nonlinear PDE setting to be involved into the output feedback synthesis over collocated state (position and/or velocity) measurements. Capabilities of the proposed synthesis are illustrated in numerical simulations.