"Crispy" to me is a dryer, brighter sound...the Tyros4 has a smooth sound, and, having played both it and the T5 through the earphones I carry in my brief case, I felt the Tyros5 was a tad less mellow...still smooth, and certainly not harsh in any way.
Neither are lacking in detail.
Ian
Ian either your ears are going or Shims, mine have gone no use asking me.