An optional matrix board of 128 x 68 outputs. Up to two IKS-6030M matrix boards can be mounted to the IXS-6700, with maximum expansion to 128 inputs x 136 outputs possible. On the other hand, IXS-6600 can accept one IKS-6030M matrix board. When this board is mounted to the IXS-6600, the matrix size becomes 64 inputs x 68 outputs. When audio signals are handled, the maximum matrix size becomes 256 inputs x 272 outputs for the IXS-6700 or 128 inputs x 136 outputs for the IXS-6600