The generation of subjectively diffuse sound fields is an essential part of creating pleasing synthetic sound fields using loudspeaker playback. A number of studies have been published presenting subjective evaluations of the diffuse sound field reproduction capabilities of different loudspeaker setups. We present a model, based on interaural coherence and interaural level difference, for estimating perceived diffuseness of synthetic sound fields evoked by an arbitrary number of transducers at different positions. The results of different loudspeaker setups and listener orientations are compared.