I have spoken with two dealers both who have heard all three amps and whose opinion I trust. Both rank them the same, MC501s best, MC452 next, and then MC402. Both still feel the MC402 represents the best bargain. Both know I have the MC501s and are not trying to sell me anything. One felt that the decision depends on the rest of the system. While he felt the MC452 is better than the MC402, the money might be better spent somewhere else in the system, like say a better CD player or such. Everyone that I have communicated with on this issue feel the MC501s are just smoother and more musical than the other two amps. The MC452 is more dynamic however. It would seem it will take the replacement for the MC501s to beat them. I have decided to sell my MC501s and wait for the replacements.