need help with my Oppo

I have a modest system that uses an Oppo disc player for both DVD and audio CD use, both 2 channel. I have a Musical Fidelity tube buffer that I use between the preamp and power amp to help take the “edge” off the Oppo when playing certain female vocals on CD. The buffer helped but sometimes the edginess is still is heard. Would I be better served by connecting the tube buffer in just the Oppo’s path and not between the amps?