I suspect that Ritz is passively bi-amping - retaining the internal crossovers and simply using separate amps to feed each set of binding posts. The significant surgery you describe is required for active bi-amping (setting up external crossovers upstream of the amps). Most folks who have experience with both approaches seem to suggest that active bi-amping offers the greatest benefits, whereas passive bi-amping yields similar results to employing a single larger amp.