Perhaps it depends on the version of the HE 400, as well as the ears of the listener. DM lists the treble of the HE 400 as one of its strengths, finding it to be "neither harsh nor abrasive":
yeah , I purchased a he400 because of its review but it's david's opinion. Many newcomers in he-400 thread are surprisesd witht these sparkly trebles ;) ... I really like now my he400 but the first time I listen to it ... it was not the case.