This paper deals with the problem of controlling aggregated linear outputs of a large-scale network to a constant reference value. A multi-output feedback controller is designed such that no information about state vector or system matrices is needed. To provide the conditions for the controller to be stable irrespectively of the gains, the passivity formalism is used and the system is shown to be Strictly Positive Real (SPR). This controller can be used to regulate average states of regions of a largescale network with control applied to nodes that lie at the boundaries of the regions.