I found the treble pretty mellow, the high mids are strong but I wouldn't say they've even reached the sparkling territory yet (or past that to harsh). OF COURSE, the sound of all headphones are changed a bit by the folds and dimensions of your ear, so I can't guarantee what it will sound like to you. This is more mellow than the HD 800, definitely not as harsh as a DT880, so if you've heard either of those this is less "harsh" by relative comparison.