Well you would get your tone first then turn down the highs. You don't go tweaking with the high shelf on. Figured that would be obvious but yeah... I should have said that. Sorry.
 
As far as highs... well my evidence is anecdotal but I certainly experience more fatigue/pain when listening to screechy stuff than say a bass track.
 
Meh.

• 85 Decibels

  "Prolonged exposure to any noise at or above 85 decibels can cause gradual hearing loss."
  

National Institute on Deafness and Other Communication Disorders
 
K-System followers take note.
 

That's why my system is calibrated at K-14 = 76dB