What is diagrammed is called "horizontal bi-amping" where one stereo amp is used for low frequencies and another for high frequencies. I think the better approach is called "vertical bi-amping" where one stereo amplifier is used for the left speaker and another for the right speaker. Obviously if you are using four identical mono amps is doesn't matter. The conventional wisdom is to use long interconnects and short speaker cables. As an added bonus, interconnects are generally a lot less expensive than speaker cables.

561, DSP5500s, DSP5000C, analog sides and rears