I was quite blown away, having only listened to cheap IEM's until I finally bought the HE-400i.   On first impression, I noticed a brilliant forward texture this headphone added to the music. It makes listening very fun and enjoyable, as bass, mids, and treble all seem to come alive from the liveliness + body of this texture. I would think of it as the opposite of being "muffled," this headphone makes the sounds come out very strong with lots of presence and movement.   As for sound quality, I think it meets all expectation of an audiophile...