This paper presents a theoretical study of active control of sound transmission through a double panel using decentralized active dampers acting between the two panels. The double panel consists of a thin aluminum plate (the source panel) and a polymer honeycomb plate (the radiating panel), coupled structurally by elastic mounts and acoustically by the air confined in a shallow cavity between the plates. The control forces are applied using a 4×4 regular array of actuators located in the cavity, which can react between the two plates. Each actuator end is equipped with a velocity sensor. The two junction velocity signals are weighted and combined into error signal. By varying the weighting factor a variety of error signals can be created. The impact of the weighting factor on the performance of the control and the stability of the feedback loops is investigated. It was found that the range of weighting factors for which the feedback loops are unconditionally stable is limited ; and the performance of the active control depends upon the weighting factor used.