A system and method to facilitate wireless testing of a radio frequency (RF) multiple-input, multiple-output (MIMO) signal transceiver device under test (DUT). With the DUT operating in a controlled electromagnetic environment, the tester transmits multiple test signals wirelessly to the DUT. Signal phases of the respective test signals transmitted by the tester are controlled in accordance with feedback signal data from the DUT. Magnitudes of the respective test signals can also be controlled in accordance with such feedback signal data, thereby enabling dynamic optimization of the wireless communication channel condition number k(H).