Man, my head is gonna explode trying to describe the sounds from these various headphones and earphones. But here goes.
The best part about the HE500's is the vocals. It's front and center and there's good air around it. Very smooth and crisp without any sibilance. There's also a nice thickness to it which brings me to the bass. The bass is full sounding and has good speed. Doesn't reach to sub-bass levels but doesn't sound like it's just mid-bass. Keeps up with the music and makes its presence known for sure. I prefer the HE500's bass over the HE400's but the HE400's are faster and has better quality. HE500's has more quantity. Treble is another strong spot because it's crisp and layered but never reaches peaky levels. The HE400's get close to peakiness and ultimately is a faster sounding headphone but doesn't have the lushness and smoothness of the HE500's. Soundstage isn't huge on the HE500's but there's a good amount of openness to the sound. That's about all that's coming to mind unless you have any specifics.
I'm sorry danny, if it makes you feel better, you're forcing people to lose their money while you lose your head. I guess it's a lose-lose.
Well not forcing, more compelling others to do so.
Either way, that's interesting, I wonder how other competitors like the on1s and m500s sound in comparison to these Hifiman.
From your description, the 400 and 500 have different sigs, but they're both pretty good?