Just listened to some Eminem(spotify), Linkin Park(lossless), Wyclef(lossy) and some good old classic rock with both Crossfade LP and ATH-M50x with no amp. Its a bad comparison in the first place since both are very different head phones with ATH-M50x costing good $80 more than I got the Crossfade LP for.
Too lazy to test them with AMPs and EQ settings since these phones are going as gifts but yeah don't try to make the Crossfade LP sound like ATH-M50x. ATH is close to belonging to a different class when compared to LP, but I would expect that for 80% more price when compared to LP, not clinical but a warm version of a clinical headphone. ATH is more like an headphone for MDR lovers who crave for more bass without any amplification.
Yeah I grew up listening to Sony MDR v6(a gift from a friend :)) and classic rock so I am biased towards that kind of sound. It was refreshing to listen to some Eminem tracks with Crossfade LP but I would sacrifice that boom for better vocal range, sound stage and instrument separation which ATH-M50x provides without any amplification or eq. I am enjoying listening to Eminem with ATH-M50x and I am not into this stuff!.
I do have couple of Sony MDR's, Grado sr80, an open air AKG(which I love) and Ultrasone PRO 750 (my work place cans!). As always this stuff is all quite subjective so...