I think either would be able to handle the ML's low impedance load comfortably, and the 92dB rating is pretty good (higher than my Paradigms). The 7125 would seem to be plenty for the Klipsch and could likely keep the Vistas happy even without bi-amping, but I've heard some mighty good things about the 7500 as well. Which is the best option? Hard to say - both are certainly good.