An improved acoustically and thermally insulating fire-retardant composite material suitable for use in structures such as buildings, appliances, and the interior passenger compartments and exterior components of automotive vehicles is provided. A differential amplification circuit unit provides an offset for one of different predetermined constant voltages supplied thereto, and outputs signals by performing a differential amplification to the different constant voltages. Methods for producing a maize plant that comprises crossing hybrid maize variety X5K664 with another maize plant.