This paper considers the homogeneous packing of binary hard spheres in an equimolar stoichiometry, and postulates the densest packing at each sphere size ratio. Monte Carlo simulated annealing optimizations are seeded with all known atomic inorganic crystal structures, and the search is performed within the degrees of freedom associated with each homogeneous AB structure type. Structures isopointal to the FeB structure type are found to have the highest packing fraction at all sphere size ratios. The optimized structures match or improve on the best previously demonstrated packings of this type, and show that compound structures can pack more densely than segregated close-packed structures at all radius ratios less than 0.62.