Pros: Wonderful sound it sends to my ear,
Cons: More bass, more soundstage, more comfort
When i first bought this headphones i feel like "What the hell did i paid this for?" The sound was like coming out of my $10 and i was disappointed, the urge to sell them piled up and i was desperately listen to my music with them (ATH M50 LE was my first over $100 headphones back then, i can't really tell what kind of sound deserve how much money), but after a few hours of burn in (more than 100 hours i think), i think "Man.. this headphones made a big difference." They are pretty good in my ears, the sound feels warm, and there are noticeable different from the original M50, i used to be amazed with my friend DT-770 250 Ohm, but now i don't really feel like that anymore.
A few thing I noticed about the difference between the M50 and LE version was the bass, i found the bass is lacking in the LE version, original M50 has more bass, and i think it was nice as well though. LE's bass more like tighter if i may say, since the original has more boom.
Second i think the details and separations are better in the LE version, i think the only thing i noticed when the first time i heard the original M50 was the bass is different in both version, i can't really recall that i was amazed with the details or something else in the original M50 (I listened to M50 LE before i listen to original M50) I've been thinking something like if LE has that kind of bass, this headphones will last longer in me before i need upgrade.
I was amazed with how M50 and M50 LE sound like, i think i can't really find a nice upgrade from them, the sound they produced are just 'different' from the other phones to me. That makes me want to own both of them for no logical reason, just because i want them.
To me M50 LE is totally amazing headphones, DT 770 250 made a nice impression to me, as well as AKG K550, Shure SRh1840, Sony SA3000, DT880 (forgot which version), Sennheisser HD-25, but i think they are not as cheap as M50 for the sound they produced, to be precise my M50 LE.
*Just for extra information, i had time to listen to AKG K550 and DT-880 + Graham Slee Solo, HD-25, ATH M50, ATH Pro700MkII + Ipod + Vbasso Magnum (i think), and Shure 1840, Sony SA3000, ATH M-50 through Sony Xperia P