I can't say I generally hear a huge difference on headphones, but when I listen on real speakers (70s Sansuis) through a real amp (http://tubedepot.com/diy-k12g.html) at a decent volume, mp3s are lacking. This is especially true compared to vinyl. I personally didn't really get why Black Sabbath were so heavy until I cranked it up on vinyl, at which point it was clear the mp3s and radio cuts were mere shadows of how it should really sound. The point being is that I'd wonder if mp3 vs. lossless might be a bit too headphone focused.