Reviving a dead thread - because it is the only thread on hi-fi with these cans as the topic. . .
These are now at Guitar Center for $50.
They are not the same as the m50s. I also have the ATH-M35s. They are not the same either. The m35 and m45 have similar signatures.
The m45s are one of the most inefficient pair of cans I've had, they need some power to drive - but once they are driven they are very good. Like m35s, they have that insanely long cable that is not removeable.
I don't have m50s to compare them to - every time I try the m50s, I think they sound great, but are not worth the asking price. The m50s and m45s look and feel nothing alike. The m45 does look like the m40 (non-removeable cable version) and the m40fs.
Everything with the m45s is clear and the bass notes sound like they are supposed to. Not bass cannons - but a wide spectrum from low-to-high with nothing overemphasized or sucked out.
Upon closer inspection, the m45s look exactly like the m40fs. The specifications are also spot-on identical, right down to driver size, frequency response, and SPL. However, they are not the same as to m40x - and it's not just the removeable cable.
Bottom line, is that if you are looking for a pair of m40fs, the m45 at Guitar Center is exactly the same thing.