The use of piezoelectric actuators for noise and vibration control purposes is well established. Recently, however, the use of negative impedance circuits for the control of such actuators has received increasing attention. This paper considers the fundamental implications of negative impedance control when used in the context of active vibration suppression on beams and plates. It is shown that action of the negative impedance control may be related to the minimization of the reactive power delivered into the structure, thereby minimizing the standing wave field. If one takes the perspective that the vibration field on a structure is composed of direct and reverberant components, then minimization of the reactive power input leads to attenuation of the reverberant component. The reverberant response is global, such that its minimization leads to global vibration minimization.