For the most basic bi-amping, you need "Y" splitter cables so that you can connect the left and right pre-amp outputs to two amp channels each. If you plan to eventually revert from bi-amping to single-amping (mono-amping? normal-amping? ... ), you probably want to leave the existing crossovers inside the speakers intact, which would rule out some of the more sophisticated forms of bi-amping. If you are curious, there are some folks around here with a good bit of knowledge about those more complex approaches.

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