Not everyone would be able to discern purported differences between the sonic signatures of high-quality solid state amplifier circuits. I believe that room interactions and source material are going to make a much bigger difference to most people than the difference between any decent receiver and an upgrade to separates. Any mid-level receiver from any of the major brands is going to deliver a satisfying audio experience with the M60 setup mentioned.
I think it depends on your listening habits, too. Most people are not going to need/want to get "the most" out of their systems approaching 100% of the time. I guess I'd reject the notion that "it's not worth doing without separates". Plenty of people enjoy Axiom setups with modestly priced receivers. Getting a receiver with pre-amp outputs allows a person to enjoy the Axiom sound immediately and still use that equipment in conjunction with a separate amp in the future if warranted.
