I have a similiar problem. That is, I have a crossover with a subwoffer output that is used in the ch 1 input. I have two subwoofers that is wired to a 4 core cable that I hooked to ch 1 speakon output on the xti 2000. No matter how I set the amp (input y, ch1 + 2, stereo, mono etc.), I am only getting output to ch1 speakers. Any help. . I have checked my cable and it is good.