Very sensitive, so don't need amping and play well from anything
Everything sounds great out of them, unlike the HE400s, which can be harsh with certain recordings
Very 'natural' sound, slightly warm if anything. Realistic and neutral.
Some treble roll off, which compliments the HE400s well. No loss of detail with the roll off and amazing detail in the midrange, more so than the HE400s.
Focus on the midrange, I suppose, but the bass is present, full and detailed. Direct comparison shows the NADs to have a fatter, rounder bass than the HE400s, but don't present the sub bass quite as vividly.
May have issues with fit if your head is big. I have no issues with the fit and find them cosy, quite tight and nicely isolating. Less weight and more snug than the HE400s.
Maybe not as exciting as the HE400s. The HE400s get more exciting the louder they go and can seem to handle limitless volume! The NADs go loud without ANY hint of harshness or pain, part of that 'nice and smooth' character which is apparent.
The HE400s have a definite signature, which permeates everything, the NADs seem to avoid lending any particular character or obvious colour to the sound, which translates as very neutral and natural to my ears.
Everything sounds right with the NADs and any attempt to EQ made them sound worse to me, which I think is a good sign.
Cable is short on the NADs, maybe too short, but apparently, replacements from other brands work too, as it's a pretty standard jack connector.
The HE400s may be a tad faster at responding and certainly sound a bit more quicker and energetic, but there is a complex lushness to the NADs that compliments the HE400s well.
I find it hard to criticise the NADs at all. It feels like I can plug them into anything anywhere and they sound great. They just look a bit daft for wearing out in public, but I don't care!
Packaging and included extras are very, very nice and give the feel of a real premium product.
As you can see, I am selling the NADs quite strongly to you. They are one of the best headphones I've ever heard and I especially like their versatility and neutrality. I really feel like I'm hearing close to what the artist intended with these cans.
For longer listening sessions, the tight pads may get warm but I havent' experienced this yet. Also, you may be disappointed if you want a bass-hyped, or generally over hyped sound - these don't do that. They present the music with warmth, elegance and clairty without even a hint of harshness EVER.