At first, I would like to stress that this all is only MY OPINION. I definitely don't wanna people think that LCD-2 are not a great headphone or that I have the ultimate truth Also, I feel the need to complete what I've said about LCD-2. Their strong points are the frequency response graph itself, especially cooperation of bass and mids (beautiful, enjoyable), AND clarity with reasonable speed. LCD-2 have low distortion levels and therefore, especially with proper amplification, they must sound very transparent and solid.
That said, they cannot quite match HD800, at least not if high-end means high-fidelity or technical brillance. This is also possible to spot when listening through difficult passages which basically means that your music makes your headphone very
busy - a lot of instruments at once, badly-mastered recordings or many layers of the same instrument, fast tempo - simply situations where you need balanced frequency response, fast impulse response and precise imaging/separation in order to still get a clear picture with all the microdetails of what is happening in front of you. HD800 are fast and advanced enough to handle everything, from metal to classical. LCD-2 are also very good but their lack or air and a bit worse impulse response plus not very good imaging, only in comparison to HD800, is quite obvious.
Another great way to illustrate what difficult music means is when you take a solo record - just one voice or one instrument. Imagine headphones playing just this one instrument... Do you
need them to be fast or precise, to image accurately? No, because all the space and time are reserved for just this one instrument... On the other hand, listen to some indie/metal record where you have several instruments and all of them can play in a very fast tempo - well, in order to not get an unlistenable mess, you need headphones which are able to distinguish every single nuance and be fast enough to separate notes in time (fast decay).
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Generally speaking, responding to the reaction above, the highest models of Stax are considered to be one of the greatest headphones ever created. That said, from what I've read, you just cannot say that Stax is going to be the very best for any single person on this planet. Haven't heard any Stax model yet unfortunately
But you can be sure that I have zero intensions to switch to any other
dynamic headphones... HD800 are perfect for me. But again, it's only my take on how I want to listen to headphones - I just prefer to be able to visualise the stage in front of me... I just love to listen to live recordings with HD800's semicircular and incredibly deep plus wide soundstage, especially in cooperation with quality hardware crossfeed, which will simply take you there. It's a 3D experience, as much as it gets with headphones. Even SR-009 is not supposed to match HD800 in terms of imaging and holographic soundstage.
It all definitely depends on your preference... I've tried to explain as much as I could why I prefer HD800 over LCD-2. However, you must realise that we are comparing two the most popular high-end offerings. Yes, people buy HD800 and LCD-2 the most, as far as I know (along with Beyerdynamic T1 I think).