From reviews, the LPs have a very muddled bass that interferes with the rest of the spectrum of sound frequencies. The LP2s are a much more refined LP that are more clear and detailed and have a lot less muddling emanating from the bass frequencies.

And just to clarify, I have not listened to any of these headphones, but I have read reviews on all of them EXTREMELY EXTENSIVELY. :P

From best to worst, here is their order: M-100 > LP2 > LP.   All these headphones are emphasized for bass. However, the LP has been reviewed as very muddy sounding. The LP2 is a refined LP that is cleaner and more detailed, with a less muddy bass. It has been reviewed to be considerably...

Quote: The two headphones look almost exactly the same. The only differences are the sound quality, the colour options, and the cliqfold hinges. Everything else is the same, and the shields and earpads from both models are inter-changable (though the M-100's earpads are ever so slightly...