In this paper, we consider the identification problem of multiinput-multioutput (MIMO) finite-impulse-response systems via second-order statistics only. By assigning different block precoders to different transmitters, we develop a new technique that allows blind MIMO channel identification up to a scalar ambiguity for each transmitter. We provide sufficient conditions for removal of the matrix ambiguity for a specific set of precoding matrices and derive a general theorem for other kinds of precoding matrices based on a reasonable conjecture. This theorem is firmly tested via numerical examples. Two potential precoding schemes are proposed, considering different ways of eliminating interblock interference. Finally, numerical results are provided to verify our analysis.