A system and method for testing multiple-input-multiple-output (MIMO) devices under test (DUTs) with multiple radio frequency (RF) signal testers. Each tester receives one or more RF signals from one or more of the DUTs, and the testers are mutually coupled in a ring such that successive ones receive a trigger input signal from an upstream tester and provide a trigger output signal to a downstream tester. Each tester is responsive to its input trigger signal and its one or more RF signals by providing its output trigger signal such that its output trigger signal has an asserted state initiated in response to an assertion of its input trigger signal and a transcending of a predetermined magnitude by at least one of the one or more RF signals.