If standard Audia® or AudiaSOLO hardware is being used, then stereo input summing is available on 12x4 configurations. However, to make use of this feature, a Fixed 12-Channel Input block must be placed in the layout. This block contains all of the features normally found on an Input block, plus Sum L-R 11 and Sum L-R 12 buttons. These buttons allow each of Inputs 11 & 12 to accept an unbalanced stereo input signal, which is then summed into mono.