I couldn't make those M2 drivers produce any slam, even with a high bass boost. You can't EQ the fundamentals, i.e. change the dynamics of a laid back signature. That's why they went back and I bought the MDR-1A instead.
Is it even possible to get slam on a neutral signature though? I think that's a holy grail demand... something will have to be coloured, it's just a matter of how much, till it spoils something else.
The MDR-1As are at the top of my list, but I can only find them for $300. I refuse to pay that much fora closed back mid-fi headphone.... Hopefully I can catch a sale when they are 200-250.