In two previous papers, we proposed an audio Informed Source Separation (ISS) system which can achieve the separation of I > 2 musical sources from linear instantaneous stationary stereo (2-channel) mixtures, based on audio signal's natural sparsity, pre-mix source signals analysis, and side-information embedding (within the mix signal). In the present paper and for the first time, we apply this system to mixtures of (up to seven) simultaneous speech signals. Compared to the reference MPEG-4 Spatial Audio Object Coding system, our system provides much cleaner separated speech signals (consistently 10.20 dB higher Signal to Interference Ratios), revealing strong potential for audio conference applications.