Any advantage to using monobloc amps

In practice: I've noticed they tend to throw up a bigger soundstage than a single-chassis equivalent.

In theory: full rated power is always available to each channel, whereas single-chassis amps demand a lot of the PS on loud & complex passages.

Libertasdon, you place the amp near the speaker and connect it with a short cable. Then you run a loooong interconnect from the preamp's output to the monoblock amp's input.

You've moved the lengthy connector cable from the speaker-amp interface to the amp-preamp interface. It's a good idea. Generally, top-quality interconnect cable is cheaper by the foot than similar speaker cable; also the amount of wire hanging off a speaker affects its impedance more than the interconnect wire affects the preamp's.