Methods, tests systems and computers for controlling power delivered to a test volume are provided. According to one aspect, an electromagnetic test system has at least one operational path having a channel emulator output, an amplifier, an attenuator and an antenna. A method includes, for a given desired output power level, C, setting a channel emulator output power to a power level B, and setting the attenuator to a setting A, such that C is a function of B and A. In such embodiments, the attenuation A is calculated based on an upper limit output power of the channel emulator and the desired output power C.