Steered response power (SRP) techniques have been well appreciated for their robustness and accuracy in estimating the direction of arrival (DOA) when a single source is active. However, by increasing the number of sources, the complexity of the resulting power map increases, making it challenging to localize the separate sources. In this work, we propose an efficient 2D histogram processing approach which is applied on the local DOA estimates, provided by SRP, and reveals the DOA of multiple audio sources in an iterative fashion. Driven by the results, we also apply the same methodology to local DOA estimates of a known subspace method and improve its accuracy. The performance of the presented algorithms is validated with numerical simulations and real measurements with a rigid spherical microphone array in different acoustical conditions: for multiple audio sources with different angular separations, various reverberation and signal-to-noise ratio (SNR) values.