Mad Dogs on the left.
Huh... INTERESTING.
Just got the leather LCD2.
Side by side comparison to the vegan LCD2...
It's subtle but... the vegan has slightly MORE bass, while the leather has slightly MORE mids.
Don't have much time to test this out today, but I will put up my findings later. As of right now, it's a miniscule difference.
They really are within a hair of each other in sound. I'll have to pay special attention to the treble range, as that's where I noted the difference before.
The leather is definitely a smidge warmer overall. It wouldn't be noticeable if you didn't compare directly like this. The vocals on the leather are fuller/slightly more organic.
The vegan is right there next to it though, and is CONSIDERABLY more comfortable. So if you want a more neutral tone, the vegan is the way to go.
edit: They're ultimately the same exact headphone. I've heard two EXACT headphones with the same exact pads sound more different than these two LCD2s with different pads. So, honestly, I'd recommend getting whichever you feel would benefit you most. I DO like the leather LCD'2s slight warmth over the vegan, so it's my keeper. But it's too close to call.