Originally Posted by davidsh
Too bad you never tried the HE-400 with an amp. Just for the sake of it.
Do not fill him with such nonsense! Grizzlybeast, take it from me, the HE-400 does not magically sound more natural with an amp. I owned the HE-400 twice for this very reason - I thought...what if I used a better amp? The verdict - nope, still sounds weird.
Grizzly, if vocals are important to you, I'd go Sennheiser. The more I listen to the X1, the less fond I am of the vocals. I do think the X1 presents vocals more naturally than the HE-400 (going by memory), but they still lack the sense of presence, body, and clarity that the HD600 and HD650 carry.
HD600 vs HD650 - HD600 has a greater sense of "clarity" and transparency, as it is more neutral. HD650 has a touch more heft in the bass, and less shine in the highs - an easier, non-fatiguing listen. But the HD600 is still a smooth, natural sounding headphone with great vocals. The bass does not extend quite as low as the HE-400, and it is quite neutral, so it may not give you the "oomph" you're looking for. But realistically, the only truly satisfying bass I've heard in a headphone is from the discontinued closed-back Denons - D2000 / D5000 / D7000. They have that "slight looseness" you mentioned in a previous post, and I agree it certainly sounds more life-like and natural than the ultra-tight bass of an open-back ortho.
Unfortunately, at this price point, there will always be compromises. Finding the headphone with the most forgivable faults for your tastes is the trick - and I think it's going to be Sennheiser for you.