As a reference, I prefered my old Audio Aero Capitole direct to a Mark Levinson amp over running the same CDP through either a Cary or BAT preamp. On the other hand, I prefered my old Wadia going through the preamp over going direct. I currently have a Resolution Audio going through a preamp (Calypso), I have never tried it direct (my systems have changed, that is why).
So, in the end I agree with the others. It depends!!!!